Math - what is the correct answer?

Parenthesis / Multiplication-Division / Add-Subtract / left to right so 60 / 5 first then 12 * 2 = 24

I was never a "math person" when I went to school. I hated the subject.

I agree with Spidey on the order of operations.

Both of my above-average Casio calculators (fx-115ES PLUS and fx-9750GII) gave the answer of 6.

On a related note...

I wonder why they allow you to use a graphing calculator (like my fx-9750GII) for college entrance exams. Seems like cheating to me as it can solve almost every math problem they give you, even giving you a natural (notebook) display (think fractions and radicals). At most you may have to do some pre-input factoring or isolation of a specific variable, or make the equation equal to zero before entering, but even some free-style input is usually accepted. This is way more than just built-in trig tables.

Also, Windows 10 has a slick graphing calculator.

6. Did not need to watch the video. Just saw the preview image. Did not use a calculator. Calculator should not be permitted in school until High School for high math. I see kids using calculator starting in kindergarten. That will not help them in life.

NFB, I worked it out correctly in my head as well, factoring vs. subtracting within the parenthesis, the only way I know it's done. The problem shows the fault of some calculators, including Windows 10 Scientific.

The calculator does not know math theory. It just does operations as you instruct it. The mathematically correct answer is 24

Oops, maybe I didn't work it correctly (6). Must come back to this.

Is it? Maybe, but what if you replace 5(7-5) by 5C, where C=(7-5)

Would you still multiply the whole by C, or treat 5C as the divisor.

If an explicit multiplication sign were shown between A/B and (C) then I would certainly treat it as being 24... with the implicit multiplication ~ it becomes ambiguous and could represent a physical situation where you have A/(BC) or one where you have AC/B, and an answer of 6 or 24 according to the meaning behind the badly written equation....

I would want to know what the application was and what resulted in that form, to be sure I was applying the order of operations not just "correctly" but appropriately and correctly, as there are competing

Yes, I have a "math background" (through/including graduate school - "A"s) and I got "6".

Why? 60+5(7-5) is not the same as 60+5x(7-5). With the "x" missing before the (), the 5(7-5) is treated as a computational group -- as like you say 5C where C is (7-5).

My calculator agrees: By the calculator 60+5x(7-5) = 24 ; whereas, by the calculator 60+5(7-5) = 6.

But, at a minimum, the video shows that some folks see it differently -- so, one needs to be careful that they are not misunderstood.

12 x 2 = 24

Watch the video.

OK. So the part I don't get is that, if you follow PEMDAS, you do 7-5 first, so that's 2. But multiplication comes before division, so shouldn't you multiply the 5x2 next, and divide 60 by 10?

Maybe I should watch the video...

edit - Oh, I see now. Multiplication/Division are left to right...

I need my old Texas Instruments calculator for this one. Back in the day, it was way cooler than a slide rule.

Here's Dell tech supports answer:

"It must be cultural!"

I quote...


Hooray for New Math
New-hoo-hoo Math
It won't do you a bit of good to review Math
It's so simple
So very simple
That only a child can do it!


Tom Leher

Multiplication and Division is same priority. Not multiplication before division. Its left to right.

You don't group 5(7-5)....you can only group what is within the parenthesis. Only if you write (5(7-5))

I came back to this while looking through a spreadsheet and I trust Allen, the former NASA engineer.

When I did this last month I also came up with 6, and I do math for a living. To me, the 5 grouped with the parenthesis gives precedence over the divisor operand, thus you do the 5 * (result of 7-5) before you do the division of 60.

You are correct, however, in saying the double parentheses would make this clearer. I disagree with the youtube video.