Pocket Mechanical Calculator - Addiator/Addifix

The Addifix/Addiator is a great little pocket calculator and is fun to use. All with no electricity!
I may or may not want to start a small collection of these now because there are some fascinating and beautiful older ones. And it's so simple and cool. Any device that makes you think "Well of course thats how it works" and is easy to use like this is great in my eyes as a mechanical device. Sure, the Comptometer is amazing for the other reasons of being complex and functional. But I can appreciate the other end of the spectrum as well.
Here's my Comptometer video if you want to know more about 9's compliment and how I did division: • 1920 Comptometer Mecha...
If you want to get one of these and support the channel you can use this link:
ebay.to/3iVVrDZ
Playlists of more stuff like this:
Calculators: • Calculators
1960s: • 1960s
Other Links
KZbin: / akbkuku
Github: github.com/AkBKukU
Thingiverse: www.thingiverse.com/AkBKukU
Patreon: / akbkuku
Discord: / discord

[@Leo-mh3cg]

Finally a Calculator for the Amish .

[@Jeffrey314159]

The Amish already use pocket electronic calculators, because they are not wired to "The Grid"

[@ryguy2006]

It's mostly a joke, chill

[@brissance]

@@Jeffrey314159 this thing does not exist never it's magic.

[@jakobxr]

@@brissancemechanical calculators are real lol

[@gregoryf3771]

Abacus has entered the chat

[@Fezzler61]

My brother was studying to be an engineer in the early 70s and showed me how to use a slide rule. Magic! Back then, proficient slide rule users would say they could get an answer faster than the early calculators. A++ video.

[@rosiefay7283]

"An answer". Yeah --- to within a few percent, and it only gave you the mantissa. You still had to determine the tens exponent by hand.

[@johnwang9914]

Electronic calculators were rare and sometimes forbidden when I was in grade school but scrap paper would be provided so in the period of time between receiving the scrap paper and the test paper was distributed, I would be writing columns of numbers along the side of the scrap paper in sequences that I had come up with to use as a lookup table. I did not know it at the time but I was effectively creating a crude slide ruler.

[@sumuduranathunga]

​@@johnwang9914in my country still not allowed to use calculators on school test. Still use logarithm tables(log books), sin, cos, tan tablets etc. But university we use scientific calculators.

[@johnwang9914]

@@sumuduranathunga It's the eternal debate, at which point does a tool prevent a written exam from evaluating a student's knowledge. I believe Neil DeGrasse Tyson once said that perhaps we should just go back to oral exams to determine if the student has understood the lessons, it would take more effort from teachers so perhaps we should hire more teachers and pay them better. Today, we're facing this "calculator" argument again with students using AI to do their homework. Is learning to use AI as a tool a hindrance to understanding the topic? Will our children become operators of technologies rather than creators of technology? We already have most people who take a jet plane to travel to Hawaii not understanding the fluid dynamics that allow a plane to fly and hence benefit from the knowledge and understanding of others, would this lead to technology regression?

[@videogamerNattie98]

The advantage is in a situation where electricity is not available where your working weather that be because the place put a restriction or rule in place weather that be temporary (Like a punishment or testing environment or permanent because of policies in place) or because of a fundamental limitation of where your at, you can use this in place of that limitation because its all mechanical engineering.

[@video99couk]

I had a single-sided "toy" version of this in the 1970s. I got really quite good at using it. Wish I hadn't lost it in the mists of time.

[@computeraidedworld1148]

Did it also come in a leather pocket and was much thinner width wise?and the hooks to carry were on the same side?

[@video99couk]

@@computeraidedworld1148 From what I remember, it was taller rather than wide, so perhaps it didn't have so many digits. I don't think it came in a sleeve at all, just clear packaging. I can only vaguely remember gold and red colouring, and instructions on the back. It would have been around 1975 because I got my first "real" calculator around the same time.

[@NeoGee]

I had a old metal one as a kid in the 70ss - early 80s. I wish my so called friend hadn't stolen it.

[@tron3entertainment]

Math person: "You can not divide by zero." Addifix user: "Hold my beer."

[@demigodgamez]

This man is too dangerous to be kept alive.

[@slappy8941]

Holy fuck what a fresh, original comment! You must be the coolest kid in your special education class.

[@metallicarchaea1820]

@@slappy8941 lol. Can't elevate oneself so must bring others down.

[@Tenxents]

​@@metallicarchaea1820cope cause unhappy 😭

[@dannydetonator]

Real maths person: only simple calculators and programms can't divide by 0. The real answer in maths and with proper coding is (+/-)INFINITY (or unknown for 0/0) 💀

[@devttyUSB0]

You probably shouldn't with this one, but i am *very* curious to see the inside of one of those!

[@TechTangents]

I actually meant to cover this in the video and forgot. The case is press fit together and I'm not sure how well it would all go back together if I tried to do it by hand. If I had one in poor cosmetic condition I would be more willing, but this one is really nice so I'd rather be sure it stays in working condition.

[@SlightlyNasty]

Going by the patent illustration at 1:00 there wouldn't be much to see - just toothed strips with the numbers punched on them and the reset handle that presumably just loops around all of them to push them back up to the top when pulled. The carry operation literally just redirects the stylus out of the teeth of one strip into the teeth on the other side of the next strip over, which is then pulled down one position.

[@devttyUSB0]

@@TechTangents Please don't destroy the working one. You wouldn't, i'm sure. ;) But if at any time you can get your hands on a shabby example, it would be cool. :)

[@Anton120698]

@@TechTangents I bought an Addifix on ebay a while back and I opend mine up. It was quite easy to do, but it can definitly scratch it up a bit (mine wasn't in a perfect condition to start with so it didnt really matter) they are extremly simple on the inside, just a couple of sliders with noches running on a kind of combe out of sheet metal.

[@Ave_humanity676]

you are the reason cool stuff is rare die out of the gene pool so we may have cool stuff in one peice in the future. thank you for my Ted speech.

[@kennethlee494]

In the 1970's they sold a item called a "Digital Calculator" or a "Magic Brain Calculator" in comic book ads, the name depended on the company selling it. The one I had was a piece of red plastic with a metal front with metal slides. It was functionally the same as this except it had the slides on one side only. I had a math teacher take mine from me one time during a test. She took it to her desk and played with it until I finished my test and brought it to her. She handed it back to me and told me that she didn't possibly see how it could help anyone with math.I went to show her how it worked and she stopped me, she told me that if she knew how it worked then she would have to fail me for cheating on a test. She was a cool teacher.

[@MatoNupai]

I got one from Spencer Gifts in the late 60s

[@MrJest2]

When I entered high school, basic digital calculators (8 digit 4 function LED models) were just becoming somewhat affordable - a couple hundred bucks, or up to a thousand in today's dollars accounting for inflation. Once in a while a kid would "borrow" his parent's calculator, and bring it to school. It was considered a cheating device, and would get one a week of suspension if caught. These days, graphing scientific calculators are considered "required school supplies" in high school. I still am conflicted about this...

[@kingdededelicious]

MrJest2 oh how the times change

[@SMGJohn]

@@MrJest2 Because the Capitalist education is only interested in teaching you the most basic knowledge to do your job. In USSR calculators were widely available for next to nothing and yet students were not allowed to use them because maths in USSR was done in a way similar to how students learn language, they had to understand the fundamental ways how mathematics worked, the rules and so on this is one of the reasons USSR and Russia today still have the best mathematicians in the world, because they do it the old way they have to understand it as a language, not just how to solve something.

[@MrCarGuy]

@@SMGJohn Some gross generalizations being made there.

[@ncot_tech]

The more I see these types of adding machine, the more I understand why CPUs operate the way they do, with registers and 2s complement. It all feels like the same operations.

[@AltimaNEO]

and literal overflows

[@NoName-md6fd]

There is no difference between the two.

[@michaelbauers8800]

The clever thing, done in computers, and by clever I also mean complex circuitry, is they use a fast adder. Without fast adder circuits, what you do is "ripple" carry. Having built this in a program called Logic World, I can attest to how slow they are. The circuit cannot add all the bits of a number in parallel, because in the worst case scenario, the high order bit would be waiting for say, the other 63 binary digits to have been added, and propagate the carry. This is glacially slow, and would cripple CPUs. Instead, by adding a lot of additional logic circuitry, they can do "carry look ahead". Allowing for more parallel operation. There's other techniques to speed up the logic for multiplication and division. Multiplication is perhaps a bit like how we learn to do things like turn 20*33 into (20 + 0)(30+3), in other words a binomial. Doing such things, you divide and conquor. Division hurts my little brain, and is clever and even more complicated than multiplication. I literally wrote some C++ code once, to simulate CPU division, but I had to totally copy an algorithm I googled, which I didn't really understand. Anyway fun stuff, and a lot of this can be learned with some google and patience. It's hard to find clear explanations of what the division circuits actually look like, though.

[@ccricers]

@@michaelbauers8800 There are some emulators that work like this, with "gate level" accuracy to mimic the operations of the CPU and other components this way. But they emulate entire 8-bit and 16-bit computer systems and most won't run in real time as current desktop CPUs still aren't fast enough for something that detailed.

[@jmtikka]

I'm not sure whether it was in my grandfather's office or on my aunt's desk but I've used one of those in the '60s as a little boy. What a wonderful machine indeed. If it was in my grandpa's office, he used it for the bookkeeping and other necessary calculations for his little cement foundry. I never knew you could actually multiply and divide on those machines. I might not remember where that machine was but I remember clearly that the casing was colored black/brass.

[@aurthorthing7403]

I had a paper and plastic wheel that did multiplication and division. It had about 23 other functions as well. I can't remember the name of it but it was from the 50's or there abouts. It also did conversions of weights and measures.... or something like that. They need to bring this tech back.

[@mattsadventureswithart5764]

Possibly a circular slide rule? I recently managed to find a circular slide rule in an antique shop and it didnt cost me much at all

[@JimmyZNJ]

I remember having one of these as a kid. Being a kid though I never appreciated just what they could do and would just play with the stylus moving the columns of numbers. To see one of these again is just WOW! Mind blown!!

[@Movie_Games]

Slide rule looks crazy. First time I saw one was in the movie Apollo 13.

[@mheermance]

I'm old enough to have used one. They took a bit of time to learn, but multiplication, division, squares, square roots, logarithms were all possible. But the falling price of calculators made them obsolete by the time I got to college.

[@Jeffrey314159]

That scene was such an exaggeration

[@bmos02]

I inherited one of these from my grandfather! I can't imagine how cool this thing was back in the day.

[@marioalday5966]

i asked for a calculator for Christmas and this was what i got. After some months of use, I became very proficient at operating this machine. I still own it. BTW, batteries are still alive after 50 years!

[@MoosesValley]

Ahhh remember the good old days in the 1960's .... when the must-have device in your pocket could do addition, subtraction, multiplication *and* division.

[@liukang3545]

you must be 120 by now then haha

[@tekvax01]

My grandma had one of these! She used it all the time. It lived on the kitchen table!

[@mojojomo6750]

I was fascinated by the concept way back in the early 80's and bought one from some magazine! It had less columns than the one shown though. I had forgotten all about it before seeing this video. Nice.

[@fredsasse9973]

What a blast from the past! I'm an old man now but as a youngster I remember my dad using an Addiator doing his work reports in his home office. He taught me how to use it, and yes, I did use that knowledge to help with a math homework question a time or two.

[@bf0189]

I love how simple and elegant it is! Very cool

[@MisterRorschach90]

Now I want someone to build a scientific calculator in this style using the even more crazy manufacturing capabilities we have today. I also need one of these now. I would carry it everywhere.

[@AnthonyDentinger]

I think one of the more advanced mechanical calculators ever made are the curtas. Expect them to be around 2k USD though.

[@abevigoda3149]

Addition and subtraction are very powerful indeed, when I was in college I found a book in the library about cordics, it took me to the conclusion that those techniques would allow me to mentally calculate trigonometric functions by means of addition and subtraction alone, I won bets against guys in college by finding the Sin, Cos or Tan of an angle in degrees or radians against their calculator with up to two decimal digits of precision, I earned some money back in the day, good 'ol times.

[@seshpenguin]

Whoa, this is pretty cool! Really simple yet ingenious design.

[@liukang3545]

HA HA

[@P_RO_]

I had a few of these as a kid. Traded junk with friends and things like this popped up sometimes. There were cheaper ones and plastic ones but these you show were the good ones. I never learned to use a slide rule but I know some old guys who can 'fly' with one. Slide rules put man on the moon so don't discount their power. I remember the pocket calculator, getting one when they became affordable, then watching them get smaller and scientifically capable. Now your phone does it all...

[@anomaly95]

Your multiplication and division tricks (or variations of them) were used by programmers of the old 8bit CPUs and microcontrollers. For example, the 6502 didn't have multiply or divide instructions.

[@Synthematix]

Divide by zero

[@vinculaomega5283]

​@@SynthematixNo you

[@AnthonyDentinger]

That remids me of a fun fact: although many microcontrollers even today don’t support floating-point operations (so you can do 12*7, but not 3.14*4.2), it is possible to ask these operations to be done using these non floating-point operations. This is called "soft-float" and, while it works, your program size usually goes way high.p when you do that.

[@nickbnash]

Thanks for the video. I have been enjoying the videos about the old counting machines. I watched your comptometer video twice to make sure I understood how everything worked. Keep it up!

[@glufke]

Can you imagine making a school test with one of those, just for the amazement of everyone... :-D

[@jussapitka6041]

He didn't show how to do trigonometric functions with it :(

[@SianaGearz]

Will probably be confiscated because of sharp metal stylus.

[@thegardenofeatin5965]

I did once use my E6B flight computer in high school physics class circa 2003. Much faster than doing the math with electronics.

[@kennethlee494]

@rustybuttpate I had a math teacher take mine from me one time during a test. She took it to her desk and played with it until I finished my test and brought it to her desk. She handed the calculator back to me and told me that she didn't possibly see how it could help anyone with math. I went to show her how it worked and she stopped me, she told me that if she knew how it worked then she would have to fail me for cheating on a test. This happened in the mid 1970's with the toy version of this sold out of comic books, she was a cool teacher.

[@FlameRat_YehLon]

@@jussapitka6041 without electronic stuffs i think the way to go is either a calculation ruler or a look up table. Or good luck finding a square root on an adder

[@Zerbey]

I didn’t realize such a thing existed, what a clever solution. I’ve had a slide rule for ages that I actually use, and it’s a great conversation piece. Now I need to find one of these!

[@OutdoorAdventureTV]

I remember having a cheap version of that when I was young. Fewer digits and a plastic stylus. I was fascinated by it. I had completely forgotten about it until this video.

[@shillcreativeworkshop]

WOW! I never thought I would ever see one of those again. I ordered one from Spensors gifts, when they were just a mail order bussiness. That was about 65 years ago.

[@haramanggapuja]

I grew up when slide rules were the fancy thing engineering students used. I am pretty sure that I saw or saw someone use an Addifix or similar device when I was a kid. Or maybe even a college student. And now that you've shown this off, well, hell, now I want one! Thanks for the nice video.

[@mandolinic]

I had a similar device when I was at school in the 1960s. It's long been lost (unlike my slide rule) but if I remember it was a lot deeper than your version and I think it had two sets of digits in each column - IIRC to add, you used the top digits to slide down and to subtract you used used the lower digits to slide up (or I may have that completely wrong!). It still had the same "wiggle" to carry overflow from one column to the next. For a simple device it's remarkably clever, and it's a lot smaller and cheaper than a fully mechanical calculator.

[@SyphistPrime]

That seems pretty handy for a time before electronic calculators. Easy addition, subtraction, and multiple with some division of you know what you are doing

[@klausbrinck2137]

One of the nicest slide calculators I´ve seen on YT. Bravo, well explained too...

[@mortarmopp3919]

What a flashback. I had one of those when I was a kid back in the 60s, though mine looked a bit different. I also had a slide rule, though smaller. I also had circular slide rule at one time. I actually enjoyed using those.

[@kensmith5694]

You can also do squareroot. It is a bit extra tricky but it can be done. Ideally you should have more than one of the devices so you can do enough digits to get really exact and have a place to build up your answer that is not just some digits on the same machine. sqrt(1234) Basically is is based on two observations. How many odd numbers you can subtract is the sqrt 16 -1 - 3 - 5 - 7 = 0 therefor sqrt(16) = 4 When you multiply a number by 100, its sqrt increases by 10 This means you can work on pairs of digits

[@yogevbocher3603]

Finally a sort of computer I used when I was young ;-))

[@agranero6]

I have two of that. I remember one my father had with many, many digits. When my son's school had an exposition of old things from students this one was a huge success.

[@runrin_]

one month from now: mechanical calculator - abacus

[@hermit3043]

mechanical calculator - Pen and Paper

[@keepermovin5906]

Mechanical calculator Clay and stylist

[@Siska0Robert]

I've actually found one very similar to this one and it was broken - the rest pull was broken inside. Fixing it was a fun little challenge! Very easy mechanism. It only had one side, but you can subtract just as well, if you get used to it.

[@HikingFeral]

Very interesting. I did not know anything like this existed so small.

[@shadowhenge7118]

My grandmother had one of these. Loved it.

[@dhanarputra555]

I can say for sure this video will be much more popular in the next 5 years or more.

[@boblewis5558]

OMG! THAT takes me back! I used to have one of those! No idea what happened to it though. One thing I'm certain about is: VERY unusually for me, I never took it apart as I could see the basis of its operation from the front and looking sideways into the slots. Mine was blue and red though. A friend of mine had the black and red. As regards slide rules ... I still have all of mine ... FIVE altogether, including the one I handed down to my youngest brother (He's 13 years my junior and also an engineer) I got it back from him years later after he'd left school and gone to college and we both by then were using calculators and I was using computers too. If you were well practiced it was easy to beat someone with a calculator back then. I still can use one!

[@camptube7621]

I had one of these as a kid. It was amazing.

[@cjkildeer5612]

I have one of these - had it since I was a kid. Mine's called a Tower 9, and it has a gold look instead of a gray one but otherwise looks exactly the same. It's still in my desk and still useful.

[@djhinderer1]

Brings back old memories, for me it was not much more than a toy to practice math. I never got the division function worked out. But it was a pretty fun device.

[@mmmsatisfaction7654]

It breaks my heart to see so many *good* content creators kind of ignored because the algorithm only favors creators with pre-existing fans. They're doing everything right and that's the worst part.

[@mheermance]

I owned one of those back in the 70's to early 80's. At the time the New York board of regents didn't allow the use of calculators on tests, but they did allow those and slide rules. So I owned both.

[@jeffbrinkerhoff5121]

I had a similar device in the 60s. Did a science fair project on calculating machines.. (got a ribbon) Thanks for this chestnut..

[@jochenstacker7448]

This is crazy, this video unlocked some extremely hazy memory of me as a child playing around with one of those. I have no idea when or where, I just remember the machine.

[@ZeroWalker26]

Man that´s one interesting hand calculator. Thanks for a great short video.

[@jasonyoung3070]

Really neat piece of old tech

[@toastnjam7384]

I had a similar one back in the late 50's. I assumed it was cheaper because it was made out of stamp metal, but it worked great. Made my math homework much easier and fun. I think I got it thru a breakfast cereal. One of those send in several cereal box tops and 50 cents deals.

[@thrillscience]

I remember in the 60s supermarkets sold low cost versions of this that just added. My parents used to get these as toys when we were kids. When we'd go shopping with mom, we'd add up the grocery bill and see if we matched the cashier.

[@MisterRorschach90]

The only thing missing from the calculator and slide rule at the end is a drafting fountain pen with a drafting ink well. I have one sitting on my shelf right in front of me. Took a while to realize what it was for. Someone got it for me because I like fountain pens. Little did he know I was also an engineering major and it was used by engineers and architects. Perfect gift.

[@Shifter-1040ST]

Wow, memories... I remember that huge Neckermann department store we had in town when I was a little boy.

[@hossnerbiz]

We talk about packaging waste today. What about that old slide rule? Cardboard slip cover, cardboard box, leather case and a plastic wrapper! I laughed watching you get it out to show! Love your videos!

[@jeffw1267]

I've got several different versions of this calculator and they're all great fun.

[@Friday_V7]

That is FASCINATING! thank you for this video! 😁

[@denniseldridge2936]

Holy moly, I hadn't thought of these things in donkey's years. I don't think I ever seriously used one, but it does ring a bell hehe.

[@raver14]

this is pretty cool! I wouldn't mind finding one of these

[@VorpalGun]

I'd love a video on how you use slide rules. I know how basic multiplication and division on slide rules, but all the more exotic scales eludes me.

[@wcsxwcsx]

Dang, we had one of those. I loved using it as a kid!

[@rts2468]

Love these videos

[@lohphat]

I have a similar unit in a gold color but it was taller and narrower; my mother had from her college years in the 1950s.

[@PierredeCur]

As my dad was an engineer, he taught me to use a slide rule before 10, and it's powerful, but it works with logarithms... My grandfather, on the contrary, did accounting and used a mechanical calculator that also did multiplications, which was quite awesome for me at that time... :-)

[@gregkocher5352]

Wow! I saw these long ago in the 70s. Used it a little.

[@TPau65]

Interesting and clever made device! Still got one of these! 😃

[@tonyrad8714]

Alwyas learn something new on every video you make. Keep them coming

[@Seele2015au]

I use mine, built to the back of a Faber-Castell slide rule, quite frequently especially when adding up my grocery cost at the supermarket.

[@filthyanimal874]

Fascinating!

[@olavschioett4101]

This is a super cool vid❤️ an interresting note is that the algorithm normaly feeds me musical stuff and i think i got this vid becurse the thumb looks like an eq pedal for a guitar😄

[@jeffw1267]

I got one similar to this (it's a Sears 6, with a similar design but only 6 digits) but it didn't come with instructions. So thank you.

[@VoidHalo]

Hey I remember these! Still got one kicking around somewhere. It's a little beat up and missing the stylus so you have to use a tooth pick. But I used to LOVE playing with it as a kid. Not the same brand or model. I believe mine was some Chinese product my Dad or Grandfather bought for their flea market stall back in the day. It was either Chinese, or Taiwanese I think but I'd have to dig it up to be sure.

[@bread9521]

Doofenshmirtz: I present you the calculatorinator Other inventors: -makes addiator- Doofenshmirtz: it would be better addinator

[@Danieltoritomayor]

A BEAUTIFUL MECHANISM ....THANKS.

[@relt_]

it looks SO modern!

[@ultrablack7271]

amazing device

[@alfblack2]

Oh dang very cool. I remember my dad having that. As a kid had no idea what it was.

[@geraldslonaker3289]

I actually have a version of one of those I took from my mom's box of junk. I remember her using it when I was kid back in the early 60's. It's pretty scratched up and my dad made her a stylus with a nail because she lost the original. Mine is longer and thinner and the addition is on top and subtraction on the bottom

[@keviiiboo7460]

This is so fascinating. I just found out these existed from a YT comment on another video.

[@dbug7276]

Beautiful ❤

[@rexjolles]

My grandpa had an old red one like this called the brain calculator. Or something and you had to use a stylus like this. He got it for work in the 1960's

[@shadowhenge7118]

I used to have one these things are so cool.

[@infographie]

Excellent.

[@DickDawsonTheShills]

WOW! way too cool. I remember them when I was a little man.

[@geormaia]

It is very good for training the mind in mathematics. If the power ever goes out, only the gears of this calculator will save us.😅✌🏽😎

[@Daedroh]

This is the coolest calculator I've ever seen. Are there other Mechanical devices like this? The other thing that has fascinated me are Watches without a need for a battery.

[@pierson9728]

that adding machine + slide rule combo is so satisfying. one does simple operations precisely, and one does complex operations approximately. what more do you need

[@jmi967]

Some slide rules had addiators built onto the back (Faber-Castell made several). Super useful since addition and subtraction aren’t slide rule friendly.

[@apmcd47]

I had a device like that, but addition and subtraction could be done without turning it upside down or over. I think the trick was that the numbers were printed twice for each column; 1-9 upwards for addition and downwards (on a different colour) for subtraction. So, for instance to subtract 6 from 9 you would load the value 9 then put the stylus into the 4 slot (which was the 6 slot on the subtract scale) and as it was in the red area you slide upwards and the result is 3. A "carry-over" slot on the bottom allows for, for instance, 23-subtract-16.

[@mandolinic]

I recall reading in the 1960s a book called (IIRC) Teach Yourself Speed Arithmetic (Teach Yourself was a very popular book series in the UK with hundreds of titles - like "For Dummies" today). This book showed you faster techniques of arithmetic by working left to right and remembering carries by underlining the previously calculated digit... All made obsolete when it became possible to condense arithmetic operations into a microchip and make an electronic calculator at an affordable price.

[@BlakeHelms]

1:33 The Palm IIIxe, my all time favorite consumer electronic device.

[@robmclaughjr]

I had one as a kid, so interesting

[@WireTeckel]

Had a similar one back in the 60's. Didn't take long to lose the stylus and resorted to toothpicks.

[@G6JPG]

Your voiceover at about 8:48 reminded me of Tom Lehrer's "New Math" - "you can't take three from two, 'cos you added one, …" or something like that. I had one of these - not for general maths, I think it had far fewer columns, more just for running totals (e. g. when shopping) - but for British currency, which before (IIRR) 1969 was not decimal!

[@TheMangeGrain]

Tried an addiator today, for the first time... Additions and substractions are pretty straightforward. When avoiding electronic calculators, I would rather fire my slide rule for multiplications and divisions. But I tried anyway. I guess I'll have to watch your video about the comptometer to understand it... But, using the repeating substraction method, divisions are very easy. 24÷6 is as easy as computing 24 - 6 - 6 - 6 - 6 = 0. Therefore quotient=4 ( number of times you can substract 6 from 24) and remainder=0. 365÷7 is cumbersome if you perform all the 52 "-7"s, but you can actually perform 365 -70 -70 -70 -70 -70 -7 -7 = 1 which yields q=52 r=1. And if you want decimals, you can divide the 10 times the remainder by 7 (10÷7 = q=1 r=3), and divide each new remainder again until you get enough decimals.

[@MariusRiley]

: My dad had one of those. When I was a kid, in the 1970s, I played with it. It was way cool.

[@chaos.corner]

I played with one of those once in my youth. I'd totally forgotten about it. I think it was a different brand.

[@salan3]

I had one of those!

[@EnderCrypt]

oh thats a fun little thing, i like it