Sine = Opposite over Hypotenuse, Cosine = Adjacent over Hypotenuse, and Tangent = Opposite over Adjacent. SOH-CAH-TOA Some Old Horses Can Always Hear Their Owner Approaching

Parenthesis, Exponents, Multiplication & Division, Addition & Subtraction. In order from left to right. Multiplication then division which ever one comes first then, addition and subtraction which ever one comes first. PEMDAS "Please excuse my dear Aunt Sally"

(high/low)' = (low * high' - high * low')/low2 "lo-di-hi minus hi-di-lo all over lo squared", lo = low, hi = high, di = derivative "Low d high, Less high d low, Draw the line, O'er squared be low."

3,14159... An excellent rational approximation of π is obtained by noting that 1 / π ≈ 1 1 3 / 3 5 5 .