# Mathematicians Don't Do Arithmetic.

"Last year there were over twenty thousand applicants, but only 11% were accepted. You can ask one of your math major friends to do that out for you, but it's not a large number of people."

That's a real quote from an educated person delivering a talk to a crowd of more than a thousand people. If you don't see anything wrong with the above quote, then congratulations: you aren't frustrated by the sort of trivial, stupid crap that I am. Otherwise, it seems that you must be frustrated by the same sort of trivial, stupid crap that I am, but I feel your pain. To those of you who belong in the first group, I'll explain why the rest of us felt like punching ourselves when we read (heard) that quote:

MATHEMATICIANS DON'T DO ARITHMETIC.

You don't need to be a mathematician, or a math major, for that matter, to understand how to do arithmetic. In fact, if you can't do arithmetic, even if your field of study or occupation is the polar opposite of mathematics (say...alpaca farming), it's not because you don't study math: it could be because you are not mathematically minded. These two things are very different. Math majors don't spend four, five, six, or more years sitting around learning to add, because this would rapidly grow very tedious. Math stops being about learning to calculate percentages and multiply fractions before you're in middle school. What mathematicians study is very different from arithmetic.

Perhaps it would be better for me to illustrate how the above quote can be modified so that it is less painful to hear. There are two ways of doing this. One of them is a bit more reasonable than the other:

Option 1 - "Last year there were over twenty thousand applicants, but only 11% were accepted. I couldn't tell you how many people were accepted, since I can't divide in my head, but it's not a large number of people."

Option 2 - "Last year there were over twenty thousand applicants, but only 11% were accepted. Let us talk about something entirely different. Consider a (pseudo-)Riemannian manifold (M, g). Show that there exists a unique symmetric connection (viz. the Levi-Civita connection) compatible with the metric g. You can ask one of your math major friends to do that out for you, but it's not a very difficult proof."

And if any of the geekier crowd is reading this, "Option 2" asks to prove the "fundamental theorem of Riemannian geometry" - a proof for which is easily Googleable.

EDIT: Some have pointed out that mathematicians obviously should know how to do arithmetic, even if they don't study it. Of course, what mathematicians study does involve arithmetic, but it's not what they do. Nobody researches addition. Asking a mathematician to divide numbers for you is like asking someone studying computer science to figure out why your computer won't boot. Sure, the computer science guy will realize you're getting that stop error because you shouldn't have installed the unsigned drivers for a shady Taiwanese midi cable. Or that you told grub your windows installation is in /dev/sda1, when it's in /dev/sda2. Or that your computer's unplugged. But computer scientists don't study tech support.