What is 15% of 20?
15% of 20 is 3. A quick mental check is 10% (2) plus 5% (1).
The answer is 3.
Result Explanation
15% of 20 = 3. If you mean 15% off 20, then 3 is the discount and the new total is 17. For that workflow, use the discount calculator.
If you’re comparing two totals (not taking a slice), use the percentage change calculator. For reverse problems, use the reverse percentage calculator.
How It Works
Step 1: Convert 15% into decimal form by dividing by 100. That gives 0.15.
Step 2: Multiply the decimal by the number: 0.15 × 20 = 3.
Full formula: (15 ÷ 100) × 20 = 3
This same method works whether you are solving shopping percentages, fee calculations, exam percentages, or general maths questions.
Strategy & Insight
A strong mental shortcut here is to split 15% into 10% + 5%. For 20, 10% is 2 and 5% is 1. Add them together and you get 3. Because both pieces are easy to find, this is one of the fastest ways to verify the answer without using a calculator.
That shortcut is commercially useful because 20 is a common reference amount. It can represent a low-cost item, a test figure in pricing, or a basic budgeting amount. When the result lands on a clean whole number like 3, you can evaluate the consequence instantly. That makes percentage thinking faster and more actionable.
Common Mistakes
- Using 15 instead of 0.15 in the multiplication.
- Answering with the post-discount total of 17 instead of the percentage amount of 3.
- Forgetting that 5% of 20 is 1 when using the mental shortcut.
- Mixing up “15% of 20” with “20 increased by 15%”.
- Treating the result as vague rather than recognising it can be read directly as £3 in money examples.
Pro Tip
When the base amount is 20, 5% is always easy to find because it is just 1/20 of 100 scaled down. That makes 15% particularly friendly: find 10%, find 5%, then combine them.
Examples
Example 1: Sale price check
A product priced at £20 with a 15% discount gives a saving of £3. The new price becomes £17.
Example 2: Commission on a small order
If a seller pays 15% commission on a £20 order, the commission amount is £3. That leaves £17 before any other deductions.
Example 3: Simple budgeting split
If you decide to put 15% of a £20 amount into savings, emergency cash, or ad spend testing, the portion set aside is £3.
Related Calculations
FAQ
What is 15% of 20?
15% of 20 is 3.
How do you work out 15% of 20?
Convert 15% to 0.15 and multiply it by 20. The answer is 3.
What is 15% off 20?
15% off 20 is a reduction of 3, leaving a final total of 17.
What is the fastest mental method for 15% of 20?
Find 10% of 20 first, which is 2, then add 5%, which is 1. Together they make 3.