The Joys of RPN

[@MathWithoutBorders]

I posted this video before learning about the HP42s simulator, called Free42. You can download it for any iPhone or Android phone, or any Windows, Mac, or Linux computer. There is no reason not to download this great RPN calculator for all your phones and computers.

[@jellybeans6533]

SwissMicro also makes the DM42, based on Free42 and a bunch of other RPN calculators, so if you want to have a new RPN calculator instead of using your phone. Also ebay has tons of used HP RPN calculators for sale. And these old HP calculators were built to last forever (well, maybe not the ones made in China after Carly Fiorina destroyed HP).

[@leeanderson5955]

Can’t believe they stopped making the HP 35s! Grrrr….

[@wotanson1]

Once you understand RPN, which takes minutes to grasp, it seems so much easier and elegant than algebraic expression. I once took a refresher algebra course in college that used the TI-83 graphing calculator. One day after class, my instructor loaned me a well worn HP 41CV and a sheaf of mimeographed papers headed "RPN made easy." I've been hook since. Thanks Mr. Kim!

[@WilliamHostman]

Many later machines use a stack, not registers, with 3-5 newest stack entries displayed. Also, new RPN calculators are available from Swiss Micro.

[@MattMcIrvin]

The X-Y-Z-T registers on these can be thought of as a little stack with a fixed depth of four levels. But HP's RPL machines (the HP-28/48/49/50 series) have a dynamic stack that can be arbitrarily deep until memory fills up, and some later ones like the Prime have a fixed 128-level stack. I'm an RPL guy myself--my go-to calculator is an emulator for the HP48GX. But RPL vs. "classic" RPN seems to be a minor split within the HP fandom. The ENTER key works slightly differently under the two systems.

[@WilliamHostman]

​@@MattMcIrvin My 48G had a keyboard failure. And they're near impossible to work on. (largely because opening the case is a destructive process... unlike by other HP calcs.) I've a cheap ($20) HP financial with RPN mode, but I miss the RPL programming. If swiss micro were to release a 48 clone, I know a LOT of gearheads who's scrimp to get one... I fear my real solution will remain the 48g emulator on the phone.

[@DanijelTurina973]

The thing is, RPN assumes you know how to solve an expression and just makes it easier for you, meaning that it actually assists you. Infix actually gets in the way most of the time, and textbook entry reduces you to entering the expression into the calculator instead of actually solving it. It's useful if you want to verify your result, but for actually solving problems, RPN forces you to break down an expression from inside out and you need to actually do the smart part of the work. I love it. I have a physical 50g and 48GX emulators on all my computers.

[@73h73373r357]

They are also very useful in business. I manage a convenience store for a day job and I love RPN. It really is faster, more intuitive, and less error prone, even for simple tasks like summing things.

[@shorthouse06]

I like RPN but I think you're vastly overstating the "smart work" that RPN makes you do. The only difference between RPN and textbook is that with RPN you have to know and be able to manually enter the order of operations. That in my opinion isn't "smart work", the smart work is actually doing the calculations which the calculator is doing for you in both cases.

[@jmfa57]

In my experience, calculator utility for most of us maxed out with the HP-25. After that, they got so sophisticated and complex that a computer became a more likely "go to" except for engineers who actually operate in the "field". I still use mine, as well as my HP-45. They serve the purpose for most of us who are blessed to have them.

[@ffggddss]

The 25C was a marvelous little (literally!) calculator, albeit with only 49 program steps, if memory serves. I also found the 67 quite useful, and later, the 41C, which was admittedly "sophisticated & complex," but expandability & accessory capability made it a hit, IMO. Maybe the most popular series was the [11, 12, 15, 16]C *; the 15C being the "scientific" programmable model of that series. To me, any perceived over-complexity of these models is offset by the fact that, with ample and continuous memory, you could key in your most useful programs once, and then just carry them with you anywhere. * Was there also a 10C? I'm not totally sure, but I think the "10" designation got re-used for an algebraic (non-RPN) model. Fred

[@leothefirst]

I recently got an HP Prime after 12 years of using a Casio with V.P.A.M. When I first heard of RPN I thought it was ridiculous to use such a method for modern calculators, but after playing around with it a bit I can see how an experience user will be able to enter calculation much faster using RPN than with any other method. I still prefer the textbook entry mode on the Prime, as it is closest to what I'm used to from my Casio days, but I'd rather use RPN than Algebraic entry any day of the week!

[@WaltKurtz68]

I bought my first HP around '91/'92, an HP-32SII. Intrigued by RPN I read the manual well , immediately saw the logic of RPN, loved it , and I never looked back. Later I also got an HP 17 BII and only ever used it in RPN mode. It just makes sense.

[@marcbarlow8099]

RPN was fantastic for use in physics.... years ago (just after the retirement of my slide ruler!)

[@danielweir5867]

Ah, the good ole slide rule! With a high-quality "slip stick" (the Georgia Tech slang for a slide rule), you could calculate out to 4 digits of accuracy if you were skilled (and lucky) enough. Of course, there was that pesky sliding piece in the middle; if you weren't careful, it would fly out and maybe hit someone. Personally I never saw that happen but I do recall some engineering students losing that vital piece, forcing them to fork over $40 for a new rule -- about $200 in today's dollars. By the late 1970s, after the HP-35 and its successors from TI and other manufacturers had come out, the Ga. Tech bookstore was selling those $40 rules for $3. By 1979, slide rules were nowhere to be found. They had been relegated to the dustbin of STEM history.

[@fouellet1701]

RPN rocks! Programmers of assembly language on mini-computers can appreciate it to its value.

[@zilog1]

FORTH is fantastic!

[@LeRoi81]

I like assembler but I don't know why I should prefer RPN. Math-like input is clearer and you can quickly see and adjust the whole expression after the input. RPN will die out like the lower programming languages.

[@CristiNeagu]

I find that when people say RPN is clearly better than alternatives, they have to make all sorts of omissions. Take 3:59. You say "Why did i have to write a symbol here?" referring to the equals sign. Well, why did you have to draw a line under 3 at 4:36? And btw, the way you wrote the addition at 4:33 is still infix. The + is between the 2 and 3. Everything you continue to say after 4:59 assumes that all other calculators are like cheap, one line, one operation calculators. This is not true. Current scientific algebraic calculators like those from Texas Instruments, HP Prime, and some Casio and Canon ones can all take that entire equation as it is written, some using CAS, some using one line equations. With RPN you have to keep track at which stage of the equation you are, what operation you need to perform, where did the number on the stack came from, etc. With standard scientific calculators you have to do none of that. You just enter the equation as shown and you solve it. No headaches. So you don't have to keep track of open brackets (5:11) since the equation does that for you. 5:18 I did. On an HP Prime, a Canon F-788dx, a TI-84, a HP 50g, and a Numworks. Very easy to do, actually. 5:29 And then you show us an RPN calculator that won't even show you what the stack contains, which means you literally have to keep track of brackets, and numbers, and operations, etc. RPN is clearly preferable over old, standard calculators that could only do a single operation at the time. Seems to me that the only advantage RPN calculators have over those simple calculators is that they can do complex calculations like the one you showed. But that's just about it. I don't find 5 ENTER 3 + to be any more natural than 5 + 3 =, in fact the latter is perhaps more natural because that's how one would write down addition. But when we get to modern scientific calculators that can handle more than 1 operation at a time, there's no competition. RPN is counter intuitive and complicated in comparison, and HP realised this, which is why RPN has not been the standard entry mode for HP calculators for a while now. And while you may argue that in the classroom RPN forces students to think about what they're doing, in the real world engineers and physicists and mathematicians use calculators precisely so they don't have to think about basic operations. They just need a number in the easiest, most efficient manner possible. And that manner is not RPN, not today.

[@pc4i]

Yeah, RPN is basically the typewriter of calculators now. Mathprint inputs just destroy the need for RPN. It’s cool and has a fundamentalist appeal, but not a real advantage these days.

[@Myrmecia]

Thank you so much! RPN just makes perfect sense in that it mirrors the way our brain works. With RPN you have two quantities and then you decide to add them, or take one from the other etc. But the brain just doesn't work algebraically: you have one quantity, then you decide what you want to do with that quantity (add, multiply etc.) then you hunt around for the second quantity on which to perform the operation. Beats me how algebraic ever caught on!

[@Poraqui]

The 6÷2(2+1) problem brought me here. I never knew there were these awesome calculators and notation!

[@williamhurst7766]

As a student, I purchased one of the first HP-45 calculators available only and directly from HP in Atlanta. I will never forget how amazed I was when I discovered the advantages of RPN.

[@schmoonkie]

I wish the asterisk was used instead of the dot to denote multiplication. That 3 dot 17 looked like 3.17. I own a 35s, 41C and a 50g. The 41C is my all time favorite.

[@FingersKungfu]

I've just started using hp 50g and now I am a fan of RPN. The only drawback of RPN is that once you get hooked, you become very irritated when you don't have an RPN calculator near by. That's why you become very reliant to your hp calculator and want to have one with you every where. : ) BTW - HP just re-release the classic hp-15C. Go get one when they are still around. I think it is the ultimate 'pocket' calculator.

[@nickgoogle4525]

Haha, that's true. The only thing I did not like about my 48GX was the size and weight. Now I have it with me all the time in an app (full emulation) on my Android smartphone... :-)

[@deltawing9]

I grew up on RPN since 1974. My first RPN calculator was the HP-45 and I loved it. Later I had more HP-s including the HP-65 with magnetic strips to carry read only programs and printed program keys. Later I used 12C to calculate rental and leasing contracts. Next had the 10-B and now I have the 17BII with infrared printer, and a 32II. Absolutely reliable tools. Before you begin a complex task you can test all components of the calculator.

[@jasong6501]

Following along on a 35s. Just taught me how to calculate without overflowing the 4 stack limit. Great vid.

[@simonbaker4]

Thanks for excellent tutorial on RPN. I think if you have a good brain, RPN is excellent. It does seem to require uninterrupted concentration because you need to visualize what's on the stack as you work. In a multitasking world, a graphics calculator lets you build the equation and if you get distracted, holds it for you. But I do love a good RPN calculator for the reasons you describe.

[@mRUSSIA]

RPN use to be a major advantage over algebraic because you don't have to worry about misplaced parenthesis and it cuts down on the complexity of equations. However, with the new textbook display algebraic calculators, and the ability to enter the equation exactly how it appears in the textbook or on paper, RPN's advantage nowadays is nullified.

[@C_L_Thomas]

Very nice introduction to the HP35S and to RPN. I went through high school and college with an HP35 (I bought from my bro-in-law for $50) and an HP29C (OMG Continuous Memory!!!) in the 1970's. Since then, with the recent release of the HP15C Limited Edition, I waited until the key issues were fixed, and I have just purchased my 21st HP Calculator. Hopefully HP will begin competing again in the calculator market and the new generation will appreciate RPN as it should be appreciated.

[@zilog1]

Oh man. Ur gonna love this old little language/os/interpreter called FORTH

[@pioneerz450]

RPN is wonderful, just started using it yesterday, today i dug up dads old HP34C 15C and 16C and i love it!

[@codycbradio]

The best HP Graphing Calculator that I've used, (the only HP Graphing Calculator that I've used) is the HP-50g. You can use both algebraic in a textbook view, and you can also calculate in rpn.

[@littleshopofelectrons4014]

I bought an HP45 in 1974 for $395 while in engineering school. That calculator was like science fiction! Prior to that I had been using a top-of-the-line Picket slide rule. I never touched a slide rule again after the HP45. I still have it. Its in perfect condition and still works. I did have to replace the NiCD battery pack.

[@Eggsr2bcrushed]

Tried typing in the equation as I saw it to my 50g and then doing it by hand, got the same answer each time. The equation writer on that thing is amazing.

[@Xanduur]

My first HP was the HP 32, purchased at University of Texas at Arlington in 1987. I miss that calculator. It traveled the world with me. I ended up selling it. /sigh.

[@RobertNugent]

Purists tell me that the 42S is the greatest calculator of all time, but the 15C is my all time favorite.

[@rogerhudson9732]

Super build quality, I still have my 16C computer science machine.

[@frankfirst6863]

I use the 42S emulator Free 42. It's the very best there is bar none IMHO. Much easier to use than a 15C for example.

[@aliensoup2420]

My first calculator was an HP-21 in 1975. RPN was cool, but a room-mate fried my calculator. So now I have a $15 TI-30xIIS solar. I can enter the equation as is from left to right with parenthesis, and got the correct answer. It's a great calculator for $15, and I've never had to change the battery after many years of use.

[@MikeKobb]

I love my HP 48SX. I used it to do the calculation that you featured here, just for fun, and of course got the same result. ;-)

[@rob876]

I bought an HP32E in 1983. I could never get used to a non reverse polish calculator after that. My next calculator was the HP41CV and then the HP48GX. I now have an HP35S but I wish I still had my HP32E. That was my favourite calculator of all time.

[@soerenwizard]

Same here. I wore out my HP32E for my engineering degree. Today I have an HP32S, from 1988. It runs fine, on the original battery!

[@amramjose]

I had an HP35E in 1978, loved it. I sold my HP32ii and regret it. Now I have a 35s and a 50G plus use the Free42 on all my computers and cell phones. Fortunately swissmicros is there to supply high quality HP clone calculators with much faster processors and more memory, plus support and warranty. I hope they make a graphing 50G clone one day!

[@Falcrist]

If you have a calculator that allows you to enter equations as written (with actual fractions rather than huge sets of brackets), this method isn't going to save you a significant number of keystrokes. In this example, I was able to enter the equation into my TI-36X with 35 keystrokes (including arrow keys). With the enter key, that brings the total to 36 keystrokes to do this calculation, rather than 37 with RPN. As far as being more intuitive... maybe. Once you get used to RPN, it's at least as fluid to use as a mathprint style calculator... but it's not that much simpler. The biggest benefit of this kind of calculator is probably for adolescents who are just learning how to work with numbers and equations. This provides a unique way of looking at calculation, and provides a peak at the stack, which is a really fundamental concept in computer science. It would probably be highly beneficial to expose a child of that age to RPN (and the slide rule and abacus).

[@julia.24]

As someone who isn't interested in computer science all that much and who's only a bit good at math compared to most people, I still really prize being introduced to RPN through the HP 33s I was told to use for my middle school calculator test competitions. When you're at that age and learning how to use a calculator more complex than a simple four function one, especially when you're learning how to interpret complex (compared to your previous arithmetic) algebraic equations and expressions and getting used to a higher level of math, I think RPN is an invaluable method to learn and stick to. It involves you throughout the process so that rather than simply inputting what you see on the page, you have to work it out and think ahead as to the order of inputs and operands. It also ensures you'll never slip up with order of operations. It may not be useful to people above that level to use regularly but it was my use of RPN that really made me enjoy math. It's certainly the middle school or high school level equivalent of the abacus.

[@tommcewan7936]

One wrong keystroke, though, and you've wasted all 33, and you can't even tell if you've made a mistake if it still spits out a number at the end, unless you can at least estimate the answer in your head. With RPN, you can see the numbers going in and coming out of every simpler operation at every step, so it's much easier to spot a mistake and quicker to correct it, especially if your RPN calculator has an undo button.

[@Jeffrey314159]

7:19 I believe I have an old calc like this one, STO and RCL for memory

[@gregfaris6959]

I know I show my age by bringing my HP-41CX into work. I have improved that image a bit by using a Swiss Micros DM41x, which is functionally identical, but looks less ancient. What I cannot understand is that I work in a room with 30 other engineers, all of whom have calculators at the ready at their desks, but NOT ONE has ever heard of RPN. And when I explain it to them, even using examples they currently have open on their desks, they completely fail to see the interest in it. They clearly see it as some gimmick from the 1970's, and probably think I have a pet rock at home (I do not, and didn't then) but anyone with any mathematical inclination should be able to easily see the interest in this form of notation. Further proof, as though we needed it, that human intellect does not develop with successive generations.....

[@karhukivi]

Well said!

[@STEAMerBear]

Our national, cultural, academic & commercial priorities were not aligned as much with mathematical rigor or excellence as with glitz. Sadly I wrote a rather lengthy (TLDR) reply that KZbin’s app decided to dump before it was posted…oh well, mostly biographical, but I watched and was forced to participate in this process in real time; it was rather depressing.

[@JWY]

In RPN your example problem is easily entered from left to right - no need to find a middle. It's easier to work in RPN then Text Book mode entry - I thought. In Text Book I had to scroll back and forth to add parenthesis around the denominator. In Text Book it's nice to see the entered problem before computation though.

[@ffggddss]

Nice coverage of the origins of RPN! It's pretty close to the way I was taught (several years before the first RPN calculators hit the consumer market). The only thing I would add is that the idea behind Polish Notation, was that an operator can be thought of as a function. This converts: 3 + 4 to +(3,4) You then notice that the parentheses aren't needed; all that *is* needed are delimiters between operators & operands. These can be commas, or any other symbol that isn't already assigned as a numeric or operator symbol. So now you might have: +,3,4 Then, as you say, the operator can be moved from front to back: 3,4,+ and voilà! RPN! And on a calculator or in a computer language, it gets implemented with a push-down ("LIFO") stack, and a palette of operators. And there is then, a lot of flexibility about those operators - they can have one or many inputs; and one or many outputs. E.g., 1-in-1-out: √x, x², sin, cos, tan, eˣ, ln(x), etc. 2-in-1-out: +, -, *, /, MOD, // (integer divide) 2-in-2-out: Rect→Pol, Pol→Rect, [the division algorithm, which I've yet to see implemented, but is quite useful at times!] 1-in-2-out: [abs, sgn], [int, frac] etc. - the possibilities are enormous! Fred

[@elye3701]

When I fill the petrol tank, I would punch in three numbers into my HP32S - the odometer reading, the price I paid and the cost per litre. The output would be a single number that told me the miles per gallon, the range before I needed to refuel and whether an oil change was due. I could have encoded a fourth piece of information in the minus sign but there was no further information I needed. Along with the other programs, I pretty much maxed out the memory. [ hp32s,programs,mileage = Axx calculates range left before empty, petrol consumption from last full tank and indicates if oil needs to be changed reg A - distance reading in hm { no mistake, a hectometre is a tenth of a kilometre } at last filling of the tank { leave out the decimal point, 12345.6 is stored as 123456 } reg B - average of last 3 consumption readings rendered to cents/hm { ie 6.2 cents per km becomes 0.62 } reg C - reading at NEXT oil change { add 5000km or whatever to reading at last oil change, follow same convention as reg A } reg Z - scratch A01 LBL A { 27 bytes, checksum CD54 } A02 40 { generates 40 x 10 = 400 km which is the safe A03 XEQ U operating range from a full tank and plug into Z, this A04 STO Z accomodates ranges from 10 to 990 km } A05 RÁ { bring down the current reading just entered } A06 RCL C { compare with reading A07 xy at next oil change A08 x>y? and set 7 decimal places instead of the normal FIX 4 A09 FIX 7 to indicate that an oil change is due } A10 RCL- A { calculate distance travelled } A11 ENTER { store this A12 ENTER for later use } A13 XEQ R { / 10 to get km } A14 IP { lose the decimals } A15 STO- Z { find remaining distance from value stored in Z and put this into Z } A16 RÁ { recall distance travelled from stack } A17 GTO C ---> { Cxx calculates the cost of petrol used } A18 RTN Bxx alternative to Axx but only calculates petrol conmsumption, used to calculate price of trip when you enter the integral kilometres travelled B01 LBL B { 9 bytes, checksum 47BC } B02 0 { must clear Z because it is used by other B03 STO Z programs as scratch } B04 RÁ { recall value entered ie distance travelled as in Axx } B05 GTO C ---> { depends on Cxx to generate the cost of petrol } B06 RTN Cxx calculates petrol consumption by multiplying with value stored in reg B and shifts this into the decimal places C01 LBL C { 10.5 bytes, checksum 0ACB } C02 RCLx B { calculates the cost } C03 IP { lose the decimals } C04 XEQ S { shift DP by 2 places left } C05 XEQ S { shift DP by another 2 places since cost is a 4 figure value } C06 RCL+ Z { add the remaining distance for final presentation } C07 RTN ] [ hp32s,programs,utilities = Qxx resets stack to 0, clears flag 3 and sets fix 4 Q01 LBL Q { 12 bytes, checksum FA84 } Q02 FIX4 Q03 0 Q04 ENTER Q05 ENTER Q06 ENTER Q07 CF 3 Q08 RTN Rxx shifts DP 1 place left by dividing by 10 R01 LBL R { 6 bytes, checksum D54E } R02 10 R03 / R04 RTN Sxx shifts DP 2 places to left by dividing by 100 S01 LBL S { 6 bytes, checksum 6ACF } S02 XEQ R S03 XEQ R S04 RTN Uxx shifts DP 1 place right by multiplying by 10 U01 LBL U { 6 bytes, checksum 1849 } U02 10 U03 x U04 RTN Vxx shifts DP 2 places right by multiplying by 100 V01 LBL V { 6 bytes, checksum DE4A } V02 XEQ U V03 XEQ U V04 RTN ] And then it died. HP "repaired" it by giving me an HP 32sII which had such a messy keyboard and then that LCD failed. While I have free42, the 32S layout was the best for me. I could even operate it eyes off. It made perfect sense that U would multiply by 10 and V would multiply by 100. upload.wikimedia.org/wikipedia/commons/thumb/9/94/Hp-32s_%28cropped%29.jpg/330px-Hp-32s_%28cropped%29.jpg But that was decades ago.

[@CalculatorObsessed]

Nice video. For RPN fans, there is a new but limited release of the Hewlett Packard HP-15C for 2023. My HP-45 is still going strong, although recently did a video with it when taking apart to clean the switch contact that had hunker up.

[@troglokev]

From the hardware developer perspective, the RPN system allows you to design much more simply. There is no need to store and parse an expression. Both numbers required for any arithmetic operation are in the stack when you press the key, so the calculation can be performed immediately, rather than stored in a string that can be arbitrarily long (no buffer overruns). In my 45 years of using them, I’ve never needed more stack than the basic four levels, and generally only use three. An elegant machine, from a more civilised age.

[@mRUSSIA]

I just purchased an HP-50G. It looks like a great machine if I can just get over the learning curve.

[@RMoribayashi]

HP finally gave in to demand and released a special edition HP-15c. It uses an ARM processor 200x faster than the original. Unfortunately the pause command has a bug. It can only pause once in a program. Any program that produced a list or matrix to copy down showed only the first result. It sold out to collectors. Users were left out again.

[@CalculatorObsessed]

There is a new Hewlett Packard HP-15C release this year 2023. A Collector’s Edition.

[@soloflo]

@@CalculatorObsessedwhat is the difference between the Collector’s and the LE from around 2011? They fixed the bug?

[@CalculatorObsessed]

@@soloflo known bugs fixed, a little faster, and a hidden 16c mode.

[@soloflo]

@@CalculatorObsessed awesome thanks! I will give it a miss. I have maybe 30 vintage HPs and 5 Swiss Micros already 😂

[@CalculatorObsessed]

@@soloflo To be fair so would I; in a similar situation.

[@febed01]

Ha ha, silly me, I got it wrong because I misread the 3*17 as 3.17 ^^ Tried with an HP41CV

[@timothyjain324]

I did the same thing haha

[@NikolajLepka]

I tried it myself both on my ti-84Plus and on an RPN app for my phone. The TI-84Plus gave me 359.40 because I forgot a few parentheses, while the RPN app gave me 30.64. You're right, RPN is much easier

[@AmenZwa]

To me, no calculator compares well against my HP-15C. Still, I do like the HP 35s, especially the HP-35-like tonneau body.

[@keithagombar5381]

in the denominator for instance the decimal point for multiply should be the "*" symbol so it should read:- (root)2*5(7+3*17)

[@mRUSSIA]

Is HP coming out with an upgrade to the 50G? It is still probably the most powerful machine out there but it is becoming dated in that the competition has new machines with a color screen and higher graph resolution.

[@commtechengineer612]

Does anyone know if HP plans to make any new pocket sized calculators? Maybe a replacement for the 35s?

[@amramjose]

No. Either buy a leftover new or used HP35s or purchase a high quality HP clone at swissmicros.com...

[@hkmix]

This video actually makes a bit of a mistake with the way RPN simplifies calculations. One of the best things about RPN is that it allows you to work entirely left-to-right without having to worry about what's where and if there are functions that need to be performed first. For example, the evaluation in the video can be done thus (E = enter): 7E3^3E2E3E5^*13E6E4^*+(root)*+2E5E7E3E17*+**(root)(divide) The newer 35s has a much more lenient memory, so this is the best way.

[@pnachtwey]

I still have a working hp35 from 1972. I was in college then.

[@ignaciogps]

Hp 67 that was for me top is available as an Iphone app (also the hp 97 that looks cool in the iPad)

[@MartinBeerbom]

Nowadays, (school) calculators have textbook entry, so one could enter the whole shebang there, and just let the calc do the work. However, it does have some downsides. 1) The given problem is already big for most (non-graphing) textbook entry calculators. It doesn't fit in the display, and editing and error handling is complicated. 2) You have to rely on the calc of the order of calculations it does. This can affect accuracy and rounding errors. 3) Most importantly: In my experience, it requires more mental discipline to enter textbook. You have to step away from your math and concentrate on operating the calc, while RPN can be "on the side". I do math tutoring, and this is indeed a big problem for many students.

[@Speedj2]

is there any other benifit to this notation? it seems to me like the reasons explained here are made obsolete by natural textbook display features on modern calcs, and yet the hp prime includes an rpn mode despite having textbook display and i see a lot of praise for rpn in forums. i was able to accurately enter this equation on both my casio fx-115es+ scientific and hp prime in only a few seconds and was even able to quickly compare what i'd entered to what was on the paper before hitting enter and getting the right answer. im not trying to be condescending or anything, im just legitimately curious as to what the big deal is, and whether this capability on my hp prime is of any use to me. or is it just a legacy feature to appeal to those who are used to it.

[@scottcollins7513]

Speedj2 I am an HP RPN fan, but I just compared number of keystrokes needed to solve this equation for 4 calculators: HP28S (RPN) = 42 (keystrokes) HP48GX (RPN) = 37 Sharp EL-W516X = 38 Casio fx-115 PLUS = 35 The HP calculators are more capable calculators​ for sure, but for most calculations I find the Casio and Sharp at least as efficient and with this sort of complex equation more efficient because you can easily compare what you entered with what you intended to enter.

[@2adamast]

I agree, I had RPN back then, but by now it is dated and there is cheaper and better.

[@mbirth]

With textbook display, you enter the formula and get a result. If you made a small mistake somewhere, you probably won't realise it. With RPN you get intermediary results for every step and are more likely to figure out when something goes wrong. Also you're forced to think about the formula instead of just copying it into the calculator.

[@timothyfidler2088]

The other advantage is that with RPN you make vastly more efficient use of memory when you program. HP calculators traditionally had much higher quality kbds with tactile feedback and more robust cases. Clearly HP have not more or less got out of the high quality scientific market - their top of line scientific calc is the HP 35S. It is a pity it does not have USB or at least RS232 and USB , mainly for saving programming work - and obviously for printing. Another thing about HP scientific calcs is they all run more or less the same way. ERGO No learning curve. You go to Prague and your calc goes under a bus. No worries. as long as you can get hold of an HP you hit the ground running.....

[@tommcewan7936]

The chief downside of RPN is that it's incredibly intuitive after actually practicing it for a while, but remarkably difficult for people to visualise as you explain it to them. You can't really tell someone the benefits, they have to *feel* them.

[@ianboard544]

What amazes me about the HP calculators is that the stack is only 4 deep - yet has worked just fine no matter how complicated the expressions got. RPN is just so much better than algebraic it's ridiculous.

[@philipparanthoiene4892]

Android mobile app "RealCalc" has RPN function.

[@comic4relief]

I have HiPER scientific app. Not the greatest calculator generally, but pretty nice RPN mode.

[@pc4i]

I think that you can be just as fast with TI's mathprint inputs/display for single calculations. Also, if you are sitting Infront of a computer, you can use something like MathCAD and that just blows any calculator out of the water. Especially when we are talking about solving engineering problems that deal with mixed unit calculations or even formulas that don't rely on actual units. I always work with a MathCAD type program for my "hand calcs" and making changes to my calculations was so simple, while my collogues who did real paper calculation with a calculator would need to redo entire calculation sets. RPN is cool, by my typewriter collection is also cool in the same way. I still enjoy using my typewriters, but I can dictate to my computer and have it type for me. If you want to take your engineering calculation game to a whole new level, learn how o use a MathCAD type program. In my opinion this is even better than excel, just because you can use units, and the flow is very similar to an actual hand calculation, which makes checking calculations much easier.

[@analog_guy]

I like MathCAD for problems and analyses that are rather involved with mulitple equations, precluding a quick answer that can be done on a hand calculator. The ability to document as you go along is very nice, as is the ability to change a value or equation and get a nearly instant answer to the whole problem without re-entering everything. However, I do get frustrated with MathCAD's difference between range variables and vectors. It seems I nearly-always set up the wrong type for the functions I intend to use. Having previously used APL where vectors and range variables are the same thing, I wish MathCAD had merged these into one construct. (Maybe that problem is fixed now. I have an old version from the days when upgrades were priced in the two-digit dollar range left of the decimal point.) For calculators, when I need a quick one-time answer, I think RPN can't be beat. To get the answer using RPN, I don't have to re-write the formula with parentheses or learn other entry methods. With RPN, I just dive in at any convenient spot and punch in a number. If I can do an operation with the number, I press the appropriate operator key. If I can't yet do an operation, then I press the ENTER key and proceed to punch in another number. Proceeding in this matter gets me to the answer without getting lost in nested parentheses. 🙂

[@pc4i]

With MathPrint on TIs, you don’t need to learn anything or rewrite the formula, just plug and play with zero nested parentheses. TI calculators even correct your input and add a multiplier when to operands are placed next to each other without a multiplication operator. The calculator does all thinking in regard to order of operations and you can verify your input, modify if needed, and do all this much faster than RPN will ever be. RPN is quick for those who know it, but it will never be as fast and efficient as MathPrint or other text book style input methods. You should really give the newer calculators a try and I think you will be surprised at the convenience and efficiency they offer.

[@cavok76]

The stack has some magic in it too, if you use it. X, y,z and t registers to its fullest

[@TheChiefSteel]

I have used an RPN calculator for 12 years. My 1987 32S II just died. I think I'm going to try to find 2007 35S. I do have an old back up that is a HP 41CX. It's real old and the buttons need to be soooo depressed. This is a great tribute to the HP RPN Calculators. The drawback is I can't pick up a standard calculator and use it. :o)

[@WeiyanWo]

I read other article about RPN also suggest start from left to right. This is natural but risk out of stack memory unless use powerful machine like g50.

[@PineappleOranges]

I don't have the HP 35s yet, but the user guide states that there are only four registers, X, Y, Z, and T. HP recommends working with the innermost parenthesis first because you save space in the register and keystrokes.

[@tommcewan7936]

There is additional memory to store variables longer-term. As I understand it, the reason there are only a handful of instant-access stack registers is that, when you're doing a calculation, you're juggling between them a lot, and most people can't keep track of more than about three or four register contents in their head whilst also planning the whole calculation overall. This is probably why the old "shell game" con very seldom uses more than three cups; any more complex and the punter (and possibly also the con artist) would probably not even attempt it for fear of losing track.

[@markdstump]

1982: When a kid in H.S told me about the HP 65...that it was programmable, that it had memory cards...I didn't believe him for a second, I was sure he was full of crap (I owned a TI-30X SOLAR). I mean he might as well have said he bought it on the moon! The next day he brought it to class and I was in LOVE! That it was his dad's OLD calculator was also incredible, I guess his dad had upgraded to the HP-67. In 1984 I got the HP 11c: I loved my 11c!!! but in the early 90s I got the 48SX, then the 48GX, I still love those, and I swear the programming is the BEST!! Programming was never more direct, syntax free, straightforward, easy to learn and use. Now I own the 49G+, and love it. My iPad has the HP 48GX and the HP Prime; my desktop has the HP 50G (same as the 49G+ really)

[@chriswalker7012]

RPN was also used by some programmable Elektronika calculators from the USSR.

[@jessstuart7495]

No parentheses needed!!! Oh yeah!!! My HP-35s is the best calculator I've ever owned. It is so convenient to whip-up a little stack program to automate routine calculations.

[@fabts4]

Just playing with a HP17BII+...is the stack length limited? Why would that be?

[@nlimchua]

Hi, I have the 32SII calc. where would the ^ key be? Or using the virtual calc used on the video, where would the ^ key be? thx.

[@mikesradiorepair]

This confirmed the reason I hate and don't use RPN calculators. I used my cheap less than $15 Casio FX115ES PLUS which has the text book display. Did the same calculation with less key strokes AND I can see the entire formula on the screen along with the answer. In the past I used RPN until better easier to use calculators came along. These days you can buy a calculator for a couple of bucks that put the antiquated RPN method of entry to shame. Don't get me wrong, I love HP calculators. Durability wise they are probably the most robustly constructed calculators there are. I have at least one of every calculator HP ever made in my collection (even a prototype). I have three calculators I use pretty much on a daily basis. A Casio FX115ES PLUS, Swiss Micros DM42 (blows the old HP42 out of the water) and a HP Prime. Of those three the Casio gets the most use because it's just plain faster to enter a equation and view the formula in case I made a mistake entering it so I can correct it. The other advantage of the Casio is the price which puts a lot of calculating power in your hands for peanuts and for the non mathematically inclined person it's easier to input a equation because it looks exactly as it does in a text book or on paper.

[@markfinn825]

Using spdt relay logic circuits are so easy to understand you

[@greenpedal370]

The Sinclair Scientific also used RPN

[@andyvan5692]

interesting video, but why use a full stop(decimal) instead of the "x" for multiply? makes it very hard to read !!(3.4, I read this as [three decimal four], not as you are saying {three times four}.

[@marcel911]

They always do that when you are multiplying two actual numbers together. Otherwise it would look like 34 it's different if it was 3x or 3t as you would know they are to be multiplied. It confused me the first time I saw it done. Notice though how the dot is in the middle (vertically). Normally the decimal place is written lower down.

[@nielsdegroot9138]

So you can't confuse it with the x variable.

[@mRUSSIA]

It is too bad that HP has can of let their calculator division fall by the wayside. They made the very best at one time even though the HP-35S & HP50G are good.

[@El_inge_987]

Will this calculator give you exact answers? when working with trig functions I many times need the answer to be exact and display squareroot of 2/2 or 3pie/2. I need a calculator that can do both exact and aproximation. Your feed back is greatly appreciated.

[@gabrieljcs11]

This is great. Thanks for the video.

[@NipkowDisk]

I've used RPN for over 24 years now and I just can't go back to using the '=' key!!! I received an HP 48SX as a present back in 1991 and have since acquired two '48GXs and a '50G, along with a few 33S and 35S versions. What REALLY stinks about the newer HP Prime calculators, is that they essentially threw User (and System) RPL out; I've written countless programs for my 48's and the 50G. I will NOT buy one of the Prime series castigators unless and until they at least have a suitable User RPL emulator.

[@wombatlover2796]

From the moment I picked up my HP 33 E about 30 years i fell in love with HP and especially RPN, as a science man.. You are so right that equal button is just so WRONG !!! On the rare occasion that I don't have my HP with me.. my boss has his 35S at work so I never go without !!!

[@Centar1964]

My $20 Casio fx-991ES PLUS C 2nd edition displays the equation and solves it correctly, I prefer it over my HP35S. I find it more intuitive even though I could work through it with the HP35S. I know the order of operations and don't need to constantly practice it. Rather just find the answer quick and simple.... it's more elegant.

[@davidcircuity6473]

HP42S is the best they ever made. Nothing comes close, even now. Too bad Hp stopped mfr; they don't know a good thing. They should make a HP42S+ with more memory.

[@renfratube]

I think the outcome is not 30.6427 but 61.2856. Who is wrong/right?

[@Damjes]

It is pronounced as written. American writing would be: woo-kah-shie-vitsch, but sh is more soft s, not sh.

[@davidschandler48]

Thanks, but are you saying that the shie is pronounced more like sie, or that the vitsch is pronounced more like vits?

[@mRUSSIA]

I just bought an HP-50G online. I already own a TI-89 Titanium which I have already owned for a while now. It is good but I have heard the HP-50G is even more powerful and flexible. I hope so or I just spend a good amount of money on a calculator that just duplicates the 89 I already own.

[@LMB222]

I RPN love!

[@comic4relief]

It is good that we have both : D

[@RMoribayashi]

If you are looking to get into RPN try out a free emulator first. The Voyager series (11, 12 15 and 16) have various PC, Mac, and Linux emulators as well as excellent iPhone and Android apps out there (*Not* the 15c from HP!) The later HP calculators (18, 28, and the 48, 49 and 50 graphing calculators) don't use RPN but RPL, a rpn version of LISP.

[@WicKedM3]

RPN must have been the shit before calculators had math print. But unfortunately with math print and being able to type it in exactly as you see it on paper, I would destory any RPN user with my Casio FX-115ES Plus

[@subscriber6181]

na

[@timothyfidler2088]

you certainly would not destroy them with your command of the Englisky language.

[@totalbrainfail1812]

I'm guessing you've never used an RPN calculator before. Although I tend to use more keystrokes on a RPN calculator, I also have always tended to be faster on one. Even with digital/emulated RPN calculators.

[@GeoCalifornian]

Mathprint and its simplicity will certainly prevent any desire for students to want to learn rpn ... rpn like HP is a relic of a bygone age. /Lonewolf

[@LeRoi81]

@@totalbrainfail1812 Speed is not everything. Like at programming, clearer, readable code is better, cause you can understand and adjust it easier afterwards. So math-print is the modern way.

[@Vermiliontea]

RPN is the way to go. Infix (algebraic notation) is an awful nightmare, by comparison. It's a great tragedy that teachers have pushed algebraic, on a totally false belief that it makes math easier to learn since it corresponds to written mathematical expressions. Generation after generation of RPN-ignorants spread the algebraic disease. So tragic.

[@ffggddss]

Algebraic treats an expression like a mindless string of symbols, copied from a page; RPN uses comprehension of what the symbols mean, to construct an order of operations to evaluate that expression. *That* is the real difference. *That* is the advantage of RPN. And that advantage increases when programming such a calculator. Fred

[@NbdUnlucky]

My precious HP48G came with an answer of 30.6427833874. Is it a junk?

[@NbdUnlucky]

I might even make a video from it if I find some camera.

[@davidschandler48]

I have Free42 (which emulates the 42S) loaded on my Linux machine (and elsewhere) and it agrees in rounding the last digit to 5. I don't know about the relative merits of the 48G and the 42S.

[@davidschandler48]

Hmmmmm...... My hand held physical 42S rounds the last digit to a 4 as does yours. I'll have to try it on a calculator capable of higher precision to see why the difference in roundoff, and which is more correct.

[@davidschandler48]

I checked the calculation with an online arbitrary precision calculator set to ~20 decimal digits precision: apfloat.appspot.com/ The result was 30.6427833874500564417, so rounding up to a 5 in the last digit is correct. From what I had read about it, I suspected that the emulator (Free42) is more precise than the physical calculator. That is correct in this instance, at least.

[@Zestyclose-Big3127]

Davic Chandler NbdUnlucky Qalculate gave me 30.6427833874500564 (set to 18 digits) edit: whoops I'm a whole month late

[@letoatreides9512]

Just bought a 35s for surveying purposes. My old Casio would have handled the entire problem just fine

[@DMWayne-ke7fl]

Sucks that they're so expensive now.

[@comic4relief]

9:23 I'm getting about 73.2

[@wisteela]

Great info

[@crystanubis]

I immediately went on Ebay to find one of the older models (with that lovely red display), they're nearly 200USD. Still a beautiful little gadget.

[@PineappleOranges]

I gave up my TI-89 Titanium for an HP-35s (using RPN mode, exclusively). I couldn't be happier. I often forget, albeit briefly, how to use regular calculators.

[@sarahmorin4577]

Ufff,that calculator became my best friend,sadly though,I will have to return it :(

[@GeoCalifornian]

Why did you have to return it?

[@sarahmorin4577]

@@GeoCalifornian because its not mine,its school property

[@k.burgess1064]

its 30.5274 i think, not 30.6427... calc98 doesn't seem very accurate..

[@leightonmitchell2564]

Freshman in college, use an hp 48g. Once you go reverse Polish notation you can’t go back.

[@PeterFraser-hp3rs]

5:00 Yeah, but the way you've written the expression, how are we supposed to know that 2.3, 13.6, 2.5 and 3.17 aren't decimals? Answer: we can't.

[@eagarde]

Only real Scientists and engineers use RPN. TI stole the market by some shady deals but HP will always be the best.

[@marinapino480]

Well... I come from Business Administration. I am not a scientist/engineer, but we also LOVE our HP RPN calculators. My 48g save my life with the exams some time ago, and my financial calculator 12c is a perpetual joy. The RPN club is kind of a sect!

[@youssefmansi2373]

boi if u dont

[@MajorPolhamus-p3k]

Mitchell Shores

[@hooya27]

LOO-kə-SHEV-itch - from en.wikipedia.org/wiki/%C5%81ukasiewicz_logic

[@leemontgomery7914]

RPN always.

[@oaktadopbok665]

Once you use RPN you'll never go back. I have an HP 11C I bought in 1983 and I still use it every day in 2018. If you do any sort of engineering or trig calculations you'd be insane to use an = key.

[@givenfirstnamefamilyfirstn3935]

Why write the 2 x 3^5 as 2.3^5 and at the same time show 2.5 (..... below the line? The dot middle or low placement and dot or comma choice just breeds ambiguity, it is as bad as different names for the elements like Tungsten and Wolfram. Science should have ONE internationally agreed standard. Got to the end and I see the 2.5 _is_ 2 x 5 and 3.17 _is_ 3 x 17. Is the spacing supposed to reveal the meaning? The written 3.17 is squeezed tight together. I did school Mathematics and Additional Mathematics over 50 years ago!

[@ignacio6655]

I have an HP 42s ;)

[@colinellicott9737]

Strange idea that the other calculation method requires parentheses, it does not, I did it without parentheses just fine. I find the rpn style confusing as I don't know where things go in the process, they just disappear. Also your written notation is confusing using . for decimals and multiplication. If error elimination is good, then you need to change some things.

[@Stain5150]

30.41411436?

[@MrUNCLESAM84]

Old timers technology, today you don't have even to enter everything it's so simple that you can just take a picture on your smart device and it'll spit out the answer for you. Also I tried it with my HP prime algebraic mode and I was done way before your RPN old timers mode.