### Famous Mnemonics PEMDAS #geek

Before they reach high school, every United States math student learns the mnemonic: **P**lease **e**xcuse **m**y **d**ear **A**unt **S**ally (illustrated above with a picture of Jane Austen) for the order of evaluation of mathematical expressions.

The **P** is for **parentheses**, reminding the student that parentheses come first. Thus 3 x (1 + 2) is 9 and not 5.

The **E** is for **exponents**, reminding the student 1 + 2 squared is 5 and not 9.

The **M** and **D** are for **multiplication** and **division**, reminding the student that 2 + 1 x 3 is 5 and not 9.

At the lowest priority are **A** and **S** for **addition** and **subtraction**, reminding the student the evaluate these operations last.

The United States approach to teaching mathematics is to maximize the material taught each year and reteach that material year after year. However, in spite of teaching this lesson a half-dozen years in a row, or more, many students miss the point. This is clearly shown by the prevalence of order-of-evaluation puzzles that return over and over to social media.