18 divided by 1/2 times 4 all over 3 =? A BASIC Math problem MANY will get WRONG!

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[Gymcoach]

I used to get F’s bc I never showed my work. This was probably the easiest one in the 6-8 I’ve done so far. In my jr. and sr. High classes I would get poor marks because I never showed my work. I didn’t even know how I came to the right conclusion and honestly, couldn’t explain how I found the right answer! I even had to repeat 2 levels of math before I could even graduate bc no one knew or even understood what Aspergers was in 1991. Thank you so much for putting these problems out there. It feels SO AMAZING 🤩 😊 to answer your questions and know in the blink of an eye what the answer is. I hope you can make an impact on all of the others out there who were either wrongly diagnosed or not diagnosed at all. We are really smart and now grateful that someone else (you) can test us and we can show you what we can do and literally how fast we can do it!! I’d love to talk to you about your experiences with people with Aspergers and Autism (high functioning Autism)❤❤❤❤❤❤❤

[kathryncooper]

I'm 75, don't remember when I last sat for a math class. I got the answer in less than 10 seconds. Contemporary education is missing something if young folks can't figure this out.

[gordonchan]

Can you understand why some people dislike math so much? Math teachers are not always good communicators, especially to young people.

[judithtaylormayo]

You are clear as mud. You made an easy thing so complicated, that I was very tempted to zap you. I was raised on B.O.D.M.A.S. (brackets, of, division, multipllication, addition and subtraction) and it was treated me correctly. so no need to change it. All in all the most simple thing to do is to convert 1/2 into 0.5 and proceed from there.

[edsinger]

In order for your answer (48) to be correct, you would need the 1/2 fraction in the numerator to be set off by parentheses. This would give you: 18 / .5 x 4 = 144. Without the parens around the 1/2 fraction, the PEMDAS rule would be 18 / 1 / 2 x 4 = 36. The correct answer is 12.

[StevenTorrey]

Why has no one noticed that he gave two different sets of answers @1:25[a) 18, b) 3, c) 12, d) 48] and @9:22 [a) 18, b) 3, c) 9, d) 12]?

[Empathiclistener]

The division sign and the slash sign both mean division so under his description of PEMDAS 18 should first be divided by 1, the answer then divided by 2 and that answer multiplied by 4, with that whole numerator divided by 3, equaling 12. PEMDAS didn't require us to do a slash division before a division-sign division, did it?

Just for fun I prefer to solve the problem like this: [(18/1) / (2x4)] all divided by 3 which would be 0.75, but that wasn't one of the multiple-choice answers.

[tomryan]

18 divided by 1/2. You have to change it to x, which is 18x 2, =36x4=144 divided by 3=48!

[johnnybonds]

I am in my late 70s with a high school education and did this in my mind in about 5 seconds, I wonder how many high school seniors now can do this?

[Chris-hfsl]

The correct way to interpret an expression is in the way that the person who wrote it intended and in this case it was intended to confuse. Sadly, some folk just enter such expressions into a calculator without any thought as to what was intended and of course the result is often wrong. Even more confusion arises with implied multiplication, for example, what is the value of 1/2𝝅f where f=10 ? This is a standard formula in electronics and it's intended to mean 1/(2πf) rather than (1/2)πf. But if you blindly follow BODMAS you'll end up with the wrong result.

[marscience]

Sorry, will have to disagree. There is no rule in PEDMAS that says to treat 1/2 differently than 1 # 2 (sorry, my keyboard does not have a divide symbol, so I use "#"). So the numerator might as well read 18 # 1 # 2 X 4 which gives 36 by PEDMAS. 36 then divided by 3 is 12. Given PEDMAS with no other rules, the answer is unambiguous. Both 12 and 48 would have to be accepted as correct. The way around this is to use parenthesis around the # (1/2) X 4. Whether it matters or not, I do have a Ph.D. in physics.

[TheBackStory]

Old school math teacher here. Purposely not using parentheses is like leaving verbs out of a sentence. No one will fill in the missing word the same way. Not to mention that the order of operations was taught differently. Just use the fricken parentheses. I did an exercise with the parents of one of my 4th graders. Gave them and a group of other adults ranging in age from 18 to 60 an math problem. ALL 6 adults got it wrong. The parents were at a BBQ and a little buzzed. The math problem caused major arguments and almost ended up in fist-a-cuffs. THIS BS IS WHY PEOPLE HATE MATH!!! It is more important to get the right answer.

[robby]

8:27 Shows (d) is the correct answer of "12" (48 is not even an option at this timestamp)
18 / 1 / 2 * 4 / 3
18 / 2 * 4 / 3
9 * 4 / 3
36 / 3
12

[ronbennett]

Grew up in the 70's and this was just simple math. I got it quickly.

[thinkcivil]

About 50 years ago I made it through business calculus, with quadratics, along with stats and geography, and graduated with a Bachelor of Science degree in Business Administration/Economics. I am currently retired, but I do not remember anyone ever mentioning PEMDAS. Before you start mocking me, I developed a degenerative neuromuscular disease, which is advancing. Along with other mental exercises, I am following this program to hopefully slow some of my cognitive loss, and not to get frustrated so easily. I just don't remember problems being presented like this back a half century ago. There always seemed to be more structure to the process, which determined which step was to be taken first, and/or next, etc.

[perryfarmer]

ISO 80000-2 states you should not use an obelus for division, you should use a solidus. In its original use the obelus was used as a ratio.

As a ratio 18 over .5 * 4 = 9
9/3 = 3

[GFlCh]

The answer is either c)12, or d)48,
depending on whether you assume there are parenthesis around the "1/2" term.

Case 1, as written:
18 ÷ 1 / 2 • 4 ÷ 3 // 18 ÷ 1 = 18
18 / 2 • 4 ÷ 3 // 18 / 2 = 9
9 • 4 ÷ 3 // 9 • 4 = 36
36 ÷ 3 // 36 ÷ 3 = 12
36 ÷ 3 = 12, answer: c)12


Case 2:
18 ÷ (1/2) • 4 ÷ 3 // 18 ÷ (1/2) = 18 • (2/1) = 18 • (2) = 36
36 • 4 ÷ 3 // 36 • 4 = 144
144 ÷ 3 // 144 ÷ 3 = 48
144 ÷ 3 = 48, answer: d)48


So there ya-go, the answer is either c)12 or d)48, depending on how John is feeling today... how "tricky" he wants to be today...





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[TomDLuv]

YES YES YES!!! Took about 45 seconds and did it in my head! 🎉🎉

[RationalSaneThinker]

I disagree with the video. The second term should not be treated as ½ or 0.5. Instead / and ÷ are identical, and both are division, as any computer user knows. So the equation is NOT (18÷½×4)÷3 = 48. Instead, it should be evaluated as (18÷1÷2×4)÷4 = (18÷2×4)÷4 = (9×4)÷4 = 36÷4 = 9. If the problem wanted the second term to be 0.5, then write ½, not 1/2. So the correct answer is 9.

[awethinic]

At 63, you made me dust off lots of old memories. But i did get the answers right. In fraction math. I just asked myself, how many half units are in 18. 36. The rest was elementary.,