Finding ten percent of an amount
Finding 10% of an amount is a quick and useful skill that comes in handy in everyday life—like when you're working out a tip in a restaurant, spotting a discount in a sale, or checking how much battery is left on your phone. It’s all about breaking things down into tenths, and it's easier than you might think! Jump to the questions
Practise now
Topic guide
What this worksheet practises
This worksheet provides practice on calculating exactly 10% of a given amount. This is the most foundational percentage skill. Because our entire number system is based on powers of 10, finding 10% is uniquely simple and serves as the primary building block for almost all other mental percentage calculations.
Key method
To find 10% of any number, you simply divide that number by 10.
- Identify the starting amount.
- Imagine the decimal point at the end of the number (if it isn't already visible).
- Move the decimal point exactly one place to the left.
- If there are empty spaces, fill them with zeroes (though usually, you are just removing a zero from the end).
Worked example
Find 10% of £450.
Step 1: The starting amount is 450.
Step 2: We must divide by 10. We can imagine the decimal point at the end: 450.0
Step 3: Move the decimal point one place to the left.
The number becomes 45.0
10% of £450 is £45.
Common mistakes to avoid
The most common mistake is confusing finding 10% with finding a tenth of a percent, or randomly moving the decimal point two places instead of one. Some students try to multiply by 0.1, which is mathematically correct but prone to error without a calculator. Always stick to dividing by 10.
Things to remember
Once you know how to find 10%, you can find almost anything else mentally. Want 20%? Double your 10% answer. Want 5%? Halve your 10% answer. Want 1%? Divide your 10% answer by 10 again.