“n is what percent of m” is (n / m) × 100. 12 is what percent of 40? 12/40 × 100 = 30%. Percents as a set are in percent problems.
Part over whole, then times 100
Keep n on top and m on the bottom. Switching them gives the inverse percent. Simple probability is the same ratio without the × 100, in simple probability.
The short list is in ACT Math formulas.
The bottom line
(part / whole) × 100. Do not flip the fraction.
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