Student resources
Grades 5-9
Percentage Formulas for Students
Percent means per 100. Percentage formulas are useful for grades, discounts, taxes, tips, sports statistics, and data questions.
Key ideas
- To find percent of a number, convert the percent to a decimal and multiply.
- To find what percent one number is of another, divide part by whole and multiply by 100.
- Percent increase compares the change to the original value.
- Discount problems usually subtract the discount amount from the original price.
Common Percentage Formulas
| Question type | Formula | Example |
|---|---|---|
| Percent of a number | percent x whole | 20% of 50 = 0.20 x 50 = 10 |
| Part as a percent | part / whole x 100 | 18 out of 20 = 18 / 20 x 100 = 90% |
| Percent increase | change / original x 100 | 40 to 50 = 10 / 40 x 100 = 25% |
| Discount price | price - discount | $80 with 25% off = $80 - $20 = $60 |
Practice questions
Find 15% of 200.
Calculation: 0.15 x 200 = 30
Answer: 30
What percent is 18 out of 24?
Calculation: 18 / 24 x 100 = 75
Answer: 75%
A price goes from $50 to $60. What is the percent increase?
Calculation: 10 / 50 x 100 = 20
Answer: 20%
A $40 item is 25% off. What is the sale price?
Calculation: 25% of 40 = 10, then 40 - 10 = 30
Answer: $30