Percentages describe a part per hundred. Once the base and comparison value are clear, most percentage questions use one short formula.
Find a percentage of a number
To find 15% of 200, multiply 200 by 15 and divide by 100. The result is 30. This is useful for tips, tax, discounts and quick estimates.
Calculate percentage change
Percentage change is the difference divided by the original value, multiplied by 100. If a value moves from 80 to 100, the increase is 20 divided by 80, or 25%.
Use percentages for discounts
A 20% discount on 100 saves 20, leaving a sale price of 80. The discount percentage applies to the original price, so record the original value before calculating a later change.
- Name the original value before calculating change.
- Keep increases and decreases tied to the correct base.
- Round currency only after the main calculation.
Frequently asked questions
What is the difference between percentage and percentage points?
Percentage measures relative change. Percentage points describe the direct difference between two percentages, such as 40% to 50% being a 10 percentage-point increase.
Can I calculate a discount and tax together?
Yes, apply each operation in order and use the updated price as the next base. The result can differ from simply adding the two percentages.