PEMDAS Mug

Please Eliminate Misleading and Dumb Acronyms from School. “PEMDAS” actually stands for an order of operations (parentheses, exponentiation, multiplication/division, addition/subtraction) and a mnemonic such as “Please Excuse My Dear Aunt Sally” is often used to remember the initials. However, instead of memorizing some arbitrary sentence, one might give a justification of the convention like this: Multiplication can be seen as repeated addition and thus takes precedence over addition. Exponentiation can be seen as repeated multiplication and thus takes precedence over multiplication. In effect, you can simplify repetitions without adding parentheses like this: 11 − 3 − 3 − 3 = 11 − 3 × 3 = 11 − 3² Makes sense, eh? “PEMDAS” can also lead people into thinking that multiplication takes precedence over division and addition over subtraction. In German schools, the line “Punkt(rechnung) vor Strich(rechnung)” (“dot (calculation) before stroke (calculation)”) is taught because multiplication is indicated with a middle dot (·) and division, at least in primary and secondary school, with a colon (:). However, multiplication is written with a cross (×) when talking about dimensions and mathematicians indicate division with a slash (/).