Guide
How to calculate percentages
A percent is one hundredth of a whole. Most calculations come down to one of three basic rules.
Part of a whole
Part = whole × percent ÷ 100. Twenty percent of CZK 1,500 is 1,500 × 20 ÷ 100 = CZK 300.
What percent
Percent = part ÷ whole × 100. If you answer 34 out of 40 questions correctly, you score 85%.
Percentage change
Change = (new - original) ÷ original × 100. A price that goes from CZK 80 to CZK 100 is up 25%. From CZK 100 to CZK 80, it's down 20%.
Watch out when working backward
If a price after a 20% discount is CZK 800, the original price isn't CZK 960. It's 800 ÷ 0.8 = CZK 1,000. The discount is taken off the original price.