Remembering the order of significance in solving equations.
Please Excuse My Dear Aunt Sally
translates to ......... Parenthesis, Exponents, Multiplication, Division, Addition, and Subtraction
ALSO
remembering Pi out to the 8th value using the phrase -- "May I have a large container of coffee?". Just count the letters in each word, and don't forget to put a decimal after counting May, which = 3
Hence Pi to the eighth value = 3.1415926
...and the one we all drilled in Algebra/Trig class in high school for remembering sine, cosine, tangent
SOH-CAH-TOA pronounced “soak a toe-uh” - Sine = Opp/Hyp, Cosine = Adj/Hyp, Tangent = Opp/Adj