15% of 20 is 3.
Worked out below step by step, with a table of related values and a live calculator so you can change the numbers.
Check it: 3 ÷ 20 × 100 = 15%, the percentage you started with.
answer = (percent ÷ 100) × value
A percentage is just a fraction of 100, so 'percent of' always means divide by 100, then multiply.
15% means 15 parts out of every 100, or 0.15 in decimal form. The word “of” means multiply, so this question converts the percentage to a decimal and multiplies it by 20.
The result, 3, is the 15% share of 20. This same method is used for tax, interest, commission, marks, proportions and many everyday percentage calculations.
A useful alternate method is to find 1% first and then scale it by 15. This exposes the place-value step clearly and is easy to check with mental arithmetic.
What is 15% of 40?
Write the percentage as a decimal: 15 ÷ 100 = 0.15. Multiply that decimal by the value: 0.15 × 40. The answer is 6. This uses the same method with different numbers, so it shows how the rule transfers instead of only repeating the original answer.
15% corresponds to the multiplier 0.15. Applying that multiplier to 20 gives 3. Because 15% is below 100%, the result should normally be smaller than 20 when 20 is positive.
The same part-of-a-whole calculation is used for tax, tips, commissions, interest estimates, marks, population shares and material allowances. The important step is identifying the base quantity before applying the percentage multiplier.
A useful alternate method is to find 1% first and then scale it by 15. This exposes the place-value step clearly and is easy to check with mental arithmetic. 1% of 20 = 20 ÷ 100 = 0.2. Multiply 0.2 by 15. 0.2 × 15 = 3.
Using 15 as the multiplier instead of converting 15% to 0.15. After correcting that setup, verify the result independently: Check it: 3 ÷ 20 × 100 = 15%, the percentage you started with.
Yes. What is 15% of 40? Write the percentage as a decimal: 15 ÷ 100 = 0.15. Multiply that decimal by the value: 0.15 × 40. The answer is 6. This uses the same method with different numbers, so it shows how the rule transfers instead of only repeating the original answer. The live calculator above lets you replace both inputs and recalculate without changing the underlying method.
15% corresponds to the multiplier 0.15. Applying that multiplier to 20 gives 3. Because 15% is below 100%, the result should normally be smaller than 20 when 20 is positive. Use that scale or ratio check together with the reverse calculation before reusing the result in another calculation.
| Percent | Of 20 |
|---|---|
| 1% | 0.2 |
| 5% | 1 |
| 10% | 2 |
| 15% | 3 |
| 20% | 4 |
| 25% | 5 |
| 30% | 6 |
| 40% | 8 |
| 50% | 10 |
| 60% | 12 |
| 75% | 15 |
| 100% | 20 |