Please Excuse My Dear Aunt Sally.

When I was a math teacher, one thing I taught frequently was the “order of operations” – the rules of the language of math. The mnemonic device to remember these rules is the word “PEMDAS,” which stands for “Please Excuse My Dear Aunt Sally.” In math-speak, “PEMDAS” means “Parentheses, Exponents, Multiplication & Division, Addition & Subtraction.” You always do parentheses before exponents, and so on. Continue reading →