5 x 8 divided by -2 / (2 + -6) =? A BASIC Math problem MANY will get WRONG!

[@alcoholfree6381]

Yeah; I got it right again, pretty good for a 70 year old retired physician who started doing math again after 50+ years not doing it! I got interested in math as I have been substitute teaching and todays students need help learning their Arithmetic. So I lucked out and found this master teacher! Thanks! -20/-4 = 5; it’s fun to get the right answer.

[@richardland9640]

I'm 72 and enjoy your videos. I find them very helpful while helping my grandson with Algebra. The answer is 5.

[@johnmorriss5308]

Typographical point: the symbol between the 5 and the 8 is NOT the symbol for the operation of multiplicationl. It's trying to be, but it's not...

[@matikramer9648]

It is old simbol of multiplication. It was such in 1960 - 1985 in eastern Europe

[@francisdelpuech6415]

@@matikramer9648it’s more looking as the letter x than the multiplication symbol and it threw me off until the very beginning of the explanation when John highlighted the operators and so I can get pass the blockade.

[@btpcmsag]

Let's hope John doesn't write the important test sheets, like final exams or SAT.

[@giannaleoci2328]

[40:(-2)]/(2-6)= (-20/-4)=5

[@AveIvy]

There was a time I was afraid of math but I've pushed myself to learn more and more. I, too, did this problem in my head and was pleased to get the answer right. BTW, I love this math channel.

[@stevejones9905]

That is a great feeling.

[@deloresford5681]

Thank you 👍🏾

[@dannmarceau]

64 this year, I did the problem in my head and am happy with my answer. Thank you for the brain exercises.

[@achimhuttermann6885]

So did i (56years old).

[@MrMousley]

5 x 8 / -2 divided by 2 + -6 This is more about getting the plus and minus right 40 / -2 divided by 2 + -6 plus divided by minus = minus -20 divided by 2 + -6 plus minus = minus -20 divided by -4 = 5 minus divided by minus = plus

[@stevenpollard5171]

You are saying plus and minus when you should be saying positive and negative. They are not the same!

[@Scott-i9v2s]

@@stevenpollard5171 Totally agreed. But the mistake is too easy to make. *At least 2* symbols exist for the division operation. *Ditto 2* symbols for the multiplication operation. PLUS, we have *4* sets of symbol-pairs for grouping. (Plus &c, &c.) Yet the *1 available* positive sign is identical to the symbol for addition? And the *1 available* negative sign is identical to the symbol for subtraction? Is the collective population of the mathematical world NUTS??? And while I am ranting anyway, this: Since the absence of an explicit sign is assumed to mean positive, an absolute value can NOT be stated without the "||" sign/operator. (And which is it, sign or symbol or operator or ...?) Also, the "=" in "X=Y" meaning both "X is equal to Y" AND "give X the value of Y"... (For the latter even Basic originally had "LET X = Y", & Algol still has X := Y".) Not to mention the absolute idiocy of "multiplication by juxtaposition"...

[@markanthony7184]

John my dear fellow, brilliant video but you're getting a bit quiet! Maybe you could turn the record level up a little? Thank you and God bless.

[@mariee.5912]

I can hear ok.

[@leslievincent20]

How about: (step1) 8/-2 =-4 (step 2) 2+(-6)=-4 (step 3) 5x(-4) divided by (-4) the (-4)'s cancel just leaving 5.

[@Scott-i9v2s]

@tabletclass Thank you for the *correct* explanation of the OoO! You know that PEMA would have been a better mnemonic, right? (For those who do NOT see this: a division is an inverted multiplication, & a subtraction is the addition of a negative.)

[@StarSong936]

I have an RPN calculator. It gives the correct answer. If you use an algebraic calculator, remember to use parenthesis around the numerator and denominator to get the correct answer. On RPN the keystrokes are 5 enter 8 X 2 CHS / 2 enter 6 CHS + / On Algebraic the keystrokes are ( 5 X 8 / 2 CHS ) / ( 2 + 6 CHS ) =

[@btpcmsag]

RPN (Reverse Polish Notation) is the boss! Hewlett Packard calculators use it, and they have a 4 register STACK, which is a great feature. The X register is the DISPLAY, always visible. Above that are Y, Z, and T, not visible, but the roll down key (R down arrow) shows you each one in turn with each stroke, 4 of which returns you to the original position. There is no = sign! 5 Enter 8 gives you 5 in Y, 8 in X, then X (times) multiplies 5×8, displaying -40. 2 CHS displays -2, then ÷ divides 40 by -2. 2 Ent 6 CHS puts 2 in Y and -6 in X, and -20 moves up to Z. Then + adds 2 + (-6) displaying -4 in X, and -20 drops down to Y. Finally, ÷ divides -20 by -4 displaying 5.

[@bigdog3628]

super simple top is just left to right in this case. so 5 times 8 is 40 then divided by negative 2 is -20 Bottom is just 2 - 6 which is -4. A negative times a negative is a positive also a negative divided by a negative is a positive. So final answer is c:) 5

[@vespa2860]

Is factorial considered a bracket?

[@flyingspirit3549]

Yeah, I also got it right again, also decent for a 70(plus!) year old computer professional who blushes to admit he was a math major many years ago. Sure glad we've got this review of material I've long forgotten.

[@Ayelmar]

At the title card, still a little rusty as I delve back into a formal algebra class, gettng c) 5 as my answer

[@joesmith-md2kt]

I did it in my head. Math 1960

[@MegaJusWright]

Yall tripping. I understand the multiplication symbol but it’s obvious in this problem that it’s being used as a multiplication symbol.

[@rodrodrigues5402]

So so tired of the negative attittude of “many will get this wrong”

[@nattyp7801]

👁just came across your channel and immediately subscribed…..❤️❤️❤️👍🏾

[@RR35592]

I don’t get why so many say this is too easy. It’s supposed to be. It’s a refresher.

[@yashathebelgianmalinois348]

I enjoy these exercises to keep the 50 yr old brain sharp.

[@matikramer9648]

Thank you

[@crinolynneendymion8755]

Mixing nomenclatures is not permitted.

[@DayanandPandey-ns5qc]

C) 5

[@DeniseHart-s4z]

c) 5

[@fernandosaenz1495]

The numerator needs parentheses, to remove anbiguity. División is not associative! If You Say that You must procede left to right or in a given order, that is a programming language, but not precisely mathematics

[@Scott-i9v2s]

*Not so* WHEN WRITTEN AS IT IS ON THAT GREENBOARD. But to write it correctly in the form of a SENTENCE, like on the line here-below: [ 5 * 8 / (-2) ] / [ 2 + (-6) ] then this problem MUST use grouping on BOTH sides of the division symbol (the symbol that is on the greenboard represented by a long horizontal line). 1 note: the "x" in "5 x 8" is ambiguous: is it the letter or the multiplication-symbol? If it is meant as multiplication-symbol, then using the "*" is NOT ambiguous. If it is meant as the LETTER, then the problem has suddenly become REALLY INTERESTING, namely a statement with an unknown that is NOT an equation...

[@GaryBricaultLive]

Since the numerator is a multiplication followed by division it does not matter which is performed first. There is no ambiguity. Ex: (5 * 8) / -2 = -20 and 5 * (8 / -2) = -20 . The denominator is defined by the line and forces it to be evaluated uniquely. @@Scott-i9v2s

[@Scott-i9v2s]

@@GaryBricaultLive The ambiguity is in reference to whether the "x" is a letter or a multiplication-symbol. Whichever one assumes makes a big difference to the problem itself. Just-because 1 assumption seems offhand to make more sense than the other is not a valid reason for that choice. That "x" might be INTENDED as a letter, in which case the NUMERATOR is: 8x5/(-2) = (8 * x * 5) / (-2) = (-20)*x

[@pedrosmith4529]

5

[@russelllomando8460]

got it 5 thanks for an easy one

[@aidagonzalez1299]

I got the right answer. I am 77

[@kjellg6532]

Me too, and I didnt need 15 minutes.

[@robertdufour2456]

I remember most of those years

[@TapioRautiainen]

Answer = 5

[@jald910]

I’m older than 64, did it in my head quickly, and got it right

[@robertoOng-xw3kc]

The answer is +5.

[@steveroads5508]

Teacher my question to you is. "What is the largest number known to man"?

[@beverleysmith8704]

Yes! 💪😂😍

[@elmelmon]

-20÷-4=5

[@gerrypanes892]

Answer is 5

[@btpcmsag]

He did it again, using an italicized x for "times" when that indicates the variable "x".

[@Mrskateboardboy]

20/3 ??

[@CuriousFocker]

Many will not understand because you have used the incorrect font for the multiplication symbol.

[@crinolynneendymion8755]

That is not a multiplication symbol; it's the letter "x". It is not the "many" who misunderand; it is the one who can't write an expression properly to go back to school and learn how to be rigorous.

[@Scott-i9v2s]

@@crinolynneendymion8755 I am beginning to wonder whether the video's author is *deliberately* setting such traps. Because they sure separate the "THINKING-CAP-ON" responders from the "by-rote-plodding" commenters... It would also give more solidity to his statement of "decades of teaching math"--ie as a WARNING to THINK, rather than as a boast. (That feeling is NOT new; this is simply the 1st time that I *air* that feeling.)

[@cwphat1]

ooooooooooooo... ok😂😂😂😂

[@alexearly1291]

-5

[@mariee.5912]

I did mentally. But my math is rusty 😆 not because of age John, but because I don't practice.

[@Sailor-Man-Dave]

C)

[@JudithMarcello-fw5oh]

-5.

[@tommythompson9565]

"Work these problems simultaneously, one step at a time." Referring to the problem being a fraction. Very confusing.

[@terry_willis]

These are too easy. In the answers, he needs a 5th choice: e) None of the above, just to spice it up a little. 😊

[@bravewave2084]

B? -5???? No soup for me! My mistake: 4 should've been -4... did in head. Probably would've made same mistake.

[@stevejones9905]

I'll share my soup with you.

[@mariee.5912]

When you divide neg by neg =positive.

[@panlomito]

-20 / -4 = 5 too easy!

[@dwaipayandattaroy9801]

How 5x is divided by natural number 😊

[@JudithMarcello-fw5oh]

Forgot a negative divided by a negative is a positive.

[@charlesthompson-uc3bp]

who cares

[@melissalevine2373]

Wrong 5

[@sheldon8115]

Aunt sally . Oh boy

[@dawnradel9008]

-5 Oops.

[@MommaBird52]

EZ!

[@jemeciasipes6388]

B

[@raya.pawley3563]

Thank you

[@jemeciasipes6388]

5

[@melissalevine2373]

-5

[@delhume2691]

5

[@mpall88]

Of course the answer is 5. The fact that it took more than 14 minutes to explain that answer is rediculous. Thumbs down.

[@rodfulford4306]

5

[@josephlaura7387]

5

[@mawavoy]

5

[@sekharb6651]

5

[@leeannkearns2273]

5

[@adan1144]

5

[@arturoyapjr3096]

5

[@heatherlussier1559]

5

[@richardshearer8623]

5

[@edwardalikor9212]

5