Percentages of amounts

Quick answer

Percentages of amounts are calculated by finding a fraction of the whole amount. For example, 10% of 50 is 5 because 10% means 10 out of 100, and 10 out of 100 of 50 is 5.

Learning outcome

By the end of this page, you will be able to find simple percentages of amounts using methods like dividing by 10, 100, or using a 10% amount to help.

• You can find 10% of any number.
• You can find 5% of any number.
• You can find 25% of any number.
• You can use 10% to help find other percentages like 20%, 30%, or 50%.

Why this matters

Understanding percentages helps you in many real-life situations. For example, when you go shopping and see a 20% discount on a toy, you need to know how much money you save. When you cook, you might need to use half a cup of sugar, which is 50% of a cup. In sports, you might see that a player scored 30% of their team's goals. Percentages help you compare parts of a whole in a simple way. This skill will help you with more advanced maths later, like ratios and proportions.

How it works

Percentages are just another way to talk about parts of a whole. The word "percent" means "per hundred". So, 50% means 50 out of 100, or half. To find a percentage of an amount, we can use a few simple steps:

1. Find 10% of the amount by dividing by 10.
2. Use this 10% to find other percentages.
3. If you need 20%, double the 10%.
4. If you need 5%, halve the 10%.
5. If you need 25%, take a quarter of the amount (divide by 4).

Examples you can see

Let’s try a few examples to see how this works:

Example 1: Find 10% of 60

To find 10% of 60, we divide by 10:

60 ÷ 10 = 6

So, 10% of 60 is 6.

Example 2: Find 20% of 60

We already know that 10% of 60 is 6.

So, 20% is 2 times 10%, which is:

6 × 2 = 12

So, 20% of 60 is 12.

Example 3: Find 5% of 60

We know 10% of 60 is 6.

So, 5% is half of 10%, which is:

6 ÷ 2 = 3

So, 5% of 60 is 3.

Example 4: Find 25% of 80

25% is a quarter of the whole amount.

So, we divide 80 by 4:

80 ÷ 4 = 20

So, 25% of 80 is 20.

Try it as a mini adventure

Adventure: The Supermarket Sale

You are going shopping with your parent or carer. You see a toy that costs £40. There is a 25% discount on the toy. You need to find out how much money you save and how much the toy costs after the discount.

1. Find 25% of £40 to see how much you save.
2. Subtract that amount from £40 to find the new price.

How to solve it:

25% of £40 means a quarter of £40.

£40 ÷ 4 = £10

You save £10.

New price = £40 – £10 = £30

So, you save £10 and the toy costs £30 after the discount.

Common mistakes

• Mistake: Thinking that 10% of 200 is 2000.
• Why it happens: Confusing multiplication with division.
• Fix: Remember that 10% means 10 out of 100, so divide by 10.
• Mistake: Forgetting that 5% is half of 10%.
• Why it happens: Not connecting percentages to simple fractions.
• Fix: Always find 10% first, then halve it for 5%.
• Mistake: Trying to multiply 10% by 10 to get 100%.
• Why it happens: Not understanding that 100% is the whole amount.
• Fix: 100% of any amount is just the amount itself.

Parent and carer guide

Helping your child with percentages is simple and fun! Here’s how:

1. Use everyday examples: When shopping, ask your child to find 10% of the price of an item.
2. Play games: Use a calculator or a number line to find percentages quickly.
3. Encourage drawing: Draw arrays or groups to show how percentages work.
4. Don’t rush: Let your child take time to think and explain their steps.
5. Be patient: Mistakes are part of learning. Celebrate correct answers and gently correct errors.

Remember, your child is learning to think in parts and wholes. This builds strong foundations for more advanced maths later.

Practice questions

1. What is 10% of 30?
2. What is 20% of 50?
3. What is 5% of 80?
4. What is 25% of 100?
5. What is 10% of 120?
6. What is 30% of 60?
7. What is 50% of 200?
8. What is 15% of 40?
9. What is 75% of 80?
10. What is 100% of 90?

Answers:

1. 3
2. 10
3. 4
4. 25
5. 12
6. 18
7. 100
8. 6
9. 60
10. 90

FAQ

What is a percentage?

A percentage is a way to show a part of a whole, using the number 100. For example, 50% means 50 out of 100, or half.

How do I find 10% of a number?

To find 10% of a number, divide the number by 10. For example, 10% of 70 is 7.

How do I find 25% of a number?

25% means a quarter, so divide the number by 4. For example, 25% of 60 is 15.

Why is it helpful to know percentages?

Percentages help us compare parts of a whole, like discounts, scores, and shares. They are used in money, shopping, cooking, and sports.

Can I use a calculator for percentages?

Yes! A calculator can help, but it's good to understand the basics first so you can check if the answer makes sense.