# Solve this equation

6 / 2(1+2) = ?

Please excuse my dear aunt Sally.

9?

I’ll be the stupid guy that says = 1

I’m sure I’m missing some associative property or some crap my son is learning in math right now.

excel says 9

How is it 9? You do 1+2 first. Then it doesn’t matter. The denominator is 6. Or if you take 6/2 = 3; then 3/(1+2)…still equals 1. Someone write out how you get to 9.

its definitely 9. you multiply from left to right. parenthesis does not set precedence if its not from within.

After the parenthesis it becomes 6 / 2 * 3, so you do it left to right. 3 * 3 = 9.

The way you’re writing it, it looks like this (6/2)*3. The way OP wrote it (or I read it), it looks like 6/(2*(1+2)). It’s a formatting issue.

Edit: Or, I’m just wrong in the way I read it.

I don’t see the parenthesis around the inside and outside 2s. If that were the case, you’d be correct.

After simplifying the (2+1) it becomes 6/2*3… PEMDAS son. Multiplication and division are interchangeable so the equation flows left to right

How can this be a CFA forum?

This really illustrates that state of 'Merika. Umm, 8 year olds in NE Asia can do this.

9

i before e except after c.

also roygbiv

do you guys remember any stuff like this from the cfa studies?

And after more than 10 years here lurking here at AF, you still haven’t figured out a way to earn the CFA charter…

#ironic

you are of course correct that according to general mathematical conventions regarding the order of operations, the answer would be 9. But other conventions do exist, for instance take a look at Feynman’s Lectures on Physics:

Equation (6.14) has the expression 1 divided by (2*Sqrt(N)) - which clearly according to general mathematical convention would be written as 1/(2*Sqrt(N)), but in the paragraph right above equation (6.14) you will notice that Richard Feynman writes 1/2*Sqrt(N) - so everything after the operator / is interpreted as being in the denominator without the need to add parenthesis. This is a convention he uses throughout the book, and is also common in other textbooks written by physicists. STL and Richard Feynman would agree that the answer is 1, purealpha and buncha 8-year old asian kids would say it’s 9. You choose your side fools

http://www.feynmanlectures.caltech.edu/I_06.html

I’m going with the 8 year old asians and PA. How could they possibly be wrong?

This extra set of the parentheses (the outside ones) that you added is what gets you 1 instead of 9. But these parentheses were not in the original equation and that’s important. It’s not just formatting. It’s the way the equation is meant to be asked. Yeah I get that. And on a text based forum it’s also the only way it can be written. I was thinking more along what would be on my kid’s homework where you have the 6 as the numerator and the rest as the denominator. So, 6 over 2*3 (that still may not make sense). In that case, the answer to a 5th grader’s homework would be 1. But I concede 9 is correct in this context…if you’re not a world renowned physists or me, that is.