Which formula correctly calculates a percentage?

Which formula correctly calculates a percentage?

• A. Divide the part by the whole and multiply by 100.
• B. Multiply the whole by the part and divide by 100.
• C. Add the part to the whole and multiply by 100.
• D. Subtract the whole from the part and multiply by 100.

Answer: (A)

To express a part as a percentage, you look at what portion of the whole the part represents and turn that fraction into a percent by multiplying by 100. This means you divide the part by the whole to get a decimal fraction, then multiply by 100 to convert that fraction to a percent. For example, if 30 of 200 are considered, 30/200 = 0.15, and 0.15 × 100 = 15%. Other formulas don’t measure the share of the total. (Whole × Part) ÷ 100 gives a different value that isn’t the same as part ÷ whole × 100 in general. Adding or subtracting the whole from the part and then multiplying by 100 creates results that don’t represent how large the part is of the whole.

To express a part as a percentage, you look at what portion of the whole the part represents and turn that fraction into a percent by multiplying by 100. This means you divide the part by the whole to get a decimal fraction, then multiply by 100 to convert that fraction to a percent. For example, if 30 of 200 are considered, 30/200 = 0.15, and 0.15 × 100 = 15%.

Other formulas don’t measure the share of the total. (Whole × Part) ÷ 100 gives a different value that isn’t the same as part ÷ whole × 100 in general. Adding or subtracting the whole from the part and then multiplying by 100 creates results that don’t represent how large the part is of the whole.