Museum maths quest: decimals

Quick answer

Decimals are numbers that are less than one whole, shown with a decimal point. You can use decimals to measure small distances, count money, or score points in games.

Learning outcome

By the end of this page, you will be able to use decimals to measure, count, and compare small parts of things – like 0.5 of a metre or 0.25 of a pound.

• You can say what 0.1, 0.2, 0.5, and 0.25 mean in real life
• You can match decimal numbers to amounts of money or parts of shapes
• You can add and subtract simple decimal numbers
• You can solve puzzles using decimal clues

Why this matters

Decimals are used everywhere! When you measure how tall you are, count your pocket money, or score points in a game, you're using decimals. In museums, artefacts might be 0.5 centimetres long or cost £0.75. Understanding decimals helps you solve puzzles, follow clues, and understand the world around you.

How it works

Decimals are numbers that are less than one whole number. They use a decimal point (.) to separate the whole number from the parts.

1. Whole numbers are like 1, 2, 3, 10, 100 – these are full things.
2. Decimals are like 0.1, 0.25, 0.5 – these are parts of a whole.
3. 0.1 means 1 part out of 10 equal parts of a whole.
4. 0.25 means 25 parts out of 100 equal parts of a whole.
5. 0.5 means 5 parts out of 10 equal parts – which is the same as half.

Examples you can see

Imagine you have a chocolate bar that is 1 whole bar. If you break it into 10 equal pieces, each piece is 0.1 of the bar. If you eat 3 pieces, you have eaten 0.3 of the bar.

Try it as a mini adventure

Join a Museum maths quest to find hidden artefacts! You are on a treasure hunt in an ancient museum. The clues tell you to find items that are:

• 0.5 metres long
• £0.25 in value
• 0.75 of the way through a puzzle

You have a special magnifying glass that helps you see parts of things. Each clue is a decimal number.

Let’s go on a journey!

1. Step 1: Find something that is 0.5 metres long. That’s the same as half a metre. You might find a small statue or a coin that is half the length of a metre stick.
2. Step 2: Look for something worth £0.25. That’s a quarter of a pound. Maybe it’s a coin or a small toy that costs 25 pence.
3. Step 3: Find a puzzle piece that is 0.75 of the way through the clue. That’s 3 parts out of 4. You might need to look for a puzzle that has 4 parts and you’ve completed 3 of them.

Can you solve all three clues?

Common mistakes

• Mistake: Thinking 0.1 is bigger than 0.5. Why it happens: Confusing the size of decimal numbers. Fix: Remember that 0.1 is one-tenth, which is smaller than 0.5, which is five-tenths.
• Mistake: Adding decimals like 0.3 + 0.2 = 0.53. Why it happens: Mixing up how to add decimals. Fix: Think of it like counting money: 30p + 20p = 50p. So 0.3 + 0.2 = 0.5.
• Mistake: Writing 0.5 as 0.50. Why it happens: Thinking extra zeros change the value. Fix: 0.5 and 0.50 are the same value – just written differently.

Parent and carer guide

Helping your child with decimals is easy and fun! Here are 5 simple ways to support them:

1. Use real money: Count out 0.25p or 0.50p to show what decimals look like in money.
2. Measure things: Use a ruler to show how 0.5 cm is half a centimetre.
3. Play games: Use board games or card games that involve counting parts or sharing items.
4. Read together: Look for decimals in recipes, clocks, or prices in shops.
5. Be patient: It’s okay to make mistakes – they help you learn!

Don’t worry if they get confused at first. Decimals are tricky at first, but with practice, they become easier!

Practice questions

1. What is 0.1 of 10 apples?
2. How much is 0.25 of £1?
3. What is 0.5 of 20 stickers?
4. What is 0.75 of 40 marbles?
5. Which is bigger: 0.3 or 0.6?

Answers:

1. 1 apple
2. 25 pence
3. 10 stickers
4. 30 marbles
5. 0.6 is bigger

FAQ

What is a decimal?

A decimal is a number that shows part of a whole, like 0.5 or 0.25. It uses a decimal point to separate the whole number from the parts.

How are decimals used in real life?

Decimals are used for money (like £0.75), measurements (like 0.5 metres), and scoring in games (like 0.25 points).

Why do we need decimals?

Decimals help us be more precise. Instead of just saying “about half”, we can say “0.5 of a cake” or “0.25 of a pound”.

How can I practice decimals at home?

You can practice by using money, measuring things around the house, or playing games with parts and sharing.

Are decimals hard to learn?

They can be tricky at first, but with practice and fun activities, they become easier!