Convert the percentage to a decimal by dividing by 100
Multiply the decimal by the money amount
For finding a percentage of a number, use: amount × percentage
For finding what percentage one amount is of another, use: part ÷ whole × 100
For increasing money by a percentage, use: amount × (1 + percentage as a decimal)
For decreasing money by a percentage, use: amount × (1 – percentage as a decimal)
For finding the original amount before a percentage change, use: final amount ÷ (1 ± percentage as a decimal)
For quick mental calculation, find 10%, 5%, 1%, then combine them
For 50%, divide by 2
For 25%, divide by 4
For 20%, divide by 5
For 1%, divide by 100