So what's a good math joke? I like this one: Young mathematician goes to first grade and the teacher asks who knows what is 1+2. She stands up and says "I don'

So what's a good math joke? I like this one: Young mathematician goes to first grade and the teacher asks who knows what is 1+2. She stands up and says "I don't know what is it, but I do know that it's the same as 2+1 as addition is commutative in the monoid of natural numbers"