How to find the percent of a number

To find a percent of a number, change the percent to a decimal and multiply: 25% of 80 = 0.25 × 80 = 20. For easy percents, use fractions or the 10% trick. This page shows both methods with a bar model, has a calculator that shows its working, and covers working backwards to find the whole.

The big idea

“25% of 80” means 25 out of every 100 parts of 80. A bar model shows it: split 80 into 100% and shade 25%.

25% of the top bar lines up with 20 of 80.

Three ways to find a percent of a number

1. Decimal and multiply

25% = 0.25; 0.25 × 80 = 20. Works for every percent.

2. Fractions for easy percents

50% = ½, 25% = ¼, 10% = 1/10, 20% = 1/5. 25% of 80 = 80 ÷ 4 = 20.

3. Build from 10%

10% of 80 is 8. 5% is half (4). So 15% = 12, 30% = 24, 35% = 28.

Percent of a number calculator

Type a percent and a number. You get the answer, the steps and a 10% check.

Working backwards: finding the whole

“8 is 5% of what number?” Divide the part by the percent as a decimal: 8 ÷ 0.05 = 160. Check: 5% of 160 is 8.

Find the whole

Percents of numbers in real life

Discount: 30% off $45 is $13.50 off, so you pay $31.50.
Tip: 15% of $40 is $4 + $2 = $6.
Tax: 8% of $25 is $2, so $27 in total.

Common mistakes

25% of 80 = 0.25Converted but didn’t multiply.Fix: multiply by the number: 0.25 × 80 = 20.

7% of 50 = 0.7 × 50Wrong decimal.Fix: 7% is 0.07: answer 3.5.

25% of 80 = 55Subtracted 25 from 80.Fix: a percent is a part, not a number to subtract.

Discount price confusedGave the discount as the price.Fix: subtract the discount from the original price.

How to teach it at home

Sale signs

Work out the sale price before you reach the till.

Restaurant tips

Use 10% and half of it for 15%.

Battery and data

“60% of 50 GB is how much?”

By grade

Grade 6 (6.RP.A.3c): find a percent of a quantity, and find the whole given a part and the percent.
Grade 7: tax, tips, discounts and percent change.
Before: percents to decimals.

Worksheets and practice

Percent of a number worksheet: printable PDF with an answer key. · Make a fresh test

Finding the whole (PDF) · All percentages

Last reviewed October 3, 2026

Questions parents ask

How do you find a percent of a number?

Change the percent to a decimal and multiply. 25% of 80 = 0.25 × 80 = 20.

How do you find 10% of a number?

Move the decimal point one place left. 10% of 340 = 34.

What is 15% of 60?

9. 10% is 6 and 5% is 3.

How do you find the whole from a percent?

Divide the part by the percent as a decimal. If 8 is 5% of a number, the number is 8 ÷ 0.05 = 160.

What grade learns percent of a number?

Grade 6 (6.RP.A.3c).