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decimals

What is a decimal

Introduce decimals as another way to write parts of a whole.

Quick answer

A decimal is another way to write parts of a whole number, like a half or a quarter, using a decimal point and digits after it. For example, 0.5 means five tenths, or half of one.

Learning outcome

By the end of this page, you will understand what decimals are and how they show parts of a whole in a different way than fractions. Success signs:
  • You can explain that a decimal is another way to show a part of a whole
  • You can read decimals like 0.25 and 0.7
  • You can match decimals to simple fractions
  • You can see decimals in everyday life, like money or measurements

Why this matters

Decimals are used everywhere in real life – in shops when you buy something, in the kitchen when you measure ingredients, and even in games and sports. Understanding decimals helps you to count, measure, and share things more easily. It’s like having a special way to say “half” or “a quarter” using numbers with a dot in the middle.

How it works

Decimals are a way to show parts of a whole using a special dot called a decimal point. The decimal point separates the whole number from the part. Let’s look at how it works: 1. The first digit after the decimal point shows how many tenths there are. 2. The second digit shows how many hundredths there are. 3. The third digit shows how many thousandths there are. Think of it like this:
  • 0.1 = one tenth
  • 0.01 = one hundredth
  • 0.001 = one thousandth
So if you have 0.5, it means 5 tenths, or half. If you have 0.25, it means 25 hundredths, or a quarter.

Examples you can see

Let’s look at some simple examples to understand decimals better. Example 1: Pizza sharing Imagine you have one pizza and you want to share it equally with a friend. That means each person gets half of the pizza. We can write this as a fraction: 1/2. We can also write it as a decimal: 0.5. Example 2: Money If you have 50 pence, that is half a pound. We can write this as a decimal: £0.50. Example 3: Measuring If you measure a pencil and it is 12.5 cm long, the 0.5 means half a centimetre more than 12 cm. Example 4: A simple grid Imagine a square divided into 10 equal parts. If 3 parts are shaded, that is 3/10 or 0.3.

Try it as a mini adventure

Adventure: The Decimal Detective You are a detective trying to find clues hidden in decimal numbers. Your mission is to find decimals that equal 1/2, 1/4, and 1/10. Here’s your mission: 1st time: Find a decimal that means half. 2nd time: Find a decimal that means a quarter. 3rd time: Find a decimal that means one-tenth. 4th time: Write the decimal for 0.75. 5th time: Match 0.2 to a fraction. How to do it: Use a number line or a grid to help you think. For example, if you know that 1/2 = 0.5, then 1/4 = 0.25.

Common mistakes

  • Mistake: Thinking that 0.5 is the same as 5. Why it happens: Confusing the decimal point with a number. Fix: Remember the decimal point separates whole from parts. 0.5 means 5 tenths, not 5 ones.
  • Mistake: Writing 0.3 as 3/100 instead of 3/10. Why it happens: Not knowing the place value of digits after the decimal point. Fix: Count the digits after the decimal point. 0.3 = 3 tenths = 3/10.
  • Mistake: Mixing up 0.1 and 0.01. Why it happens: Confusion between tenths and hundredths. Fix: Remember: 0.1 = one tenth, 0.01 = one hundredth.

Parent and carer guide

As a parent or carer, you can help your child understand decimals by:
  • Using everyday examples like money, cooking, or measuring
  • Practicing reading decimals together, like 0.25 or 0.7
  • Playing games where you find decimals in real life, such as on a shop price tag or a ruler
  • Encouraging your child to explain how decimals work in their own words
  • Being patient and praising effort, not just correct answers
Remember: It’s normal for children to get confused at first. Keep the learning fun and practical, and your child will grow more confident with decimals over time.

Practice questions

  1. What is 1/2 written as a decimal?
  2. What is 1/4 written as a decimal?
  3. What is 1/10 written as a decimal?
  4. What is 0.50 in fraction form?
  5. Match 0.75 to a fraction.
Answers:
  1. 0.5
  2. 0.25
  3. 0.1
  4. 1/2
  5. 3/4

FAQ

What does a decimal point mean?

The decimal point is a small dot that separates the whole number from the part. For example, in 2.5, the 2 is the whole number and 0.5 is the part.

Why do we use decimals?

Decimals help us show parts of a whole more clearly, especially when we are dealing with money, measurements, or sharing things. They are easier to use in some situations than fractions.

Can decimals be more than one?

Yes! Decimals can be more than one. For example, 1.5 means one and five tenths, or one and a half.

Are decimals the same as fractions?

Decimals and fractions are different ways to show the same thing. For example, 0.5 is the same as 1/2.

How do I read decimals?

You read decimals by saying the number and then the place value. For example, 0.7 is "seven tenths" and 0.25 is "twenty-five hundredths".