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Percent Word Problems
Most percent word problems are one of three types: find a percent of a number, find what percent one number is of another, or find the whole when you know a part. Turning the percent into a decimal makes each one quick.
For: Grade 6 and 7 students and anyone working with discounts, tax or tips.
The rules
- Percent means "out of 100": 35% = 35/100 = 0.35.
- Part = percent × whole.
- Percent = part ÷ whole × 100.
- Percent change = (new − old) ÷ old × 100.
Worked examples
Example 1: A $40 shirt is 25% off. What is the sale price?
- 25% of 40 = 0.25 × 40 = 10.
- Subtract the discount: 40 − 10 = 30.
Answer: $30
Example 2: 18 of the 24 students in a class walk to school. What percent is that?
- Part ÷ whole = 18 ÷ 24 = 0.75.
- 0.75 × 100 = 75.
Answer: 75%
Example 3: A meal costs $50. You leave an 18% tip. How much is the tip?
- 18% = 0.18.
- 0.18 × 50 = 9.
Answer: $9
Example 4: A town grew from 2,000 to 2,300 people. What is the percent increase?
- Change: 2,300 − 2,000 = 300.
- 300 ÷ 2,000 = 0.15.
- 0.15 × 100 = 15.
Answer: 15% increase
Practice problems
- What is 20% of 85?
- 12 is what percent of 48?
- 30% of a number is 21. What is the number?
- A $60 game is 15% off. Sale price?
- A price goes from $80 to $60. Percent change?
Show answers
- 17
- 25%
- 70
- $51
- 25% decrease
Frequently asked questions
How do you find the original price after a discount?
Divide the sale price by (1 − discount). For example, a $36 price after 10% off came from 36 ÷ 0.9 = $40.
How do you turn a percent into a decimal?
Divide by 100, which moves the decimal point two places left: 7% = 0.07, 125% = 1.25.
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