Space explorer maths quest: decimals

Quick answer

Decimals help us measure and count parts of a whole, like when you need to know how far your rocket went or how much alien juice you have. You can think of decimals as tenths and hundredths, like sharing a pizza into 10 pieces or 100 pieces.

Learning outcome

By the end of this page, you will be able to understand and use decimals to measure small parts of a whole, like distances, money, and scores in your space explorer adventure.

• You can show tenths and hundredths using drawings or objects.
• You can compare decimal numbers using place value.
• You can solve simple problems with decimals using real-life examples.
• You can play a game to practice using tenths and hundredths.

Why this matters

Decimals are used in many exciting places, like space missions! When astronauts travel to other planets, they need to know exact distances. When you buy something, you might pay £2.50 or £3.99. In games, scores can be 10.5 points or 12.7 points. Understanding decimals helps you solve problems in space and in everyday life.

How it works

Decimals are numbers that have a point, like 0.5 or 1.25. The point separates the whole number from the parts. The first number after the point is called the tenths place, and the second number is the hundredths place.

1. Think of a whole number as a whole pizza.
2. Divide it into 10 equal slices – each slice is one-tenth or 0.1.
3. Divide one slice into 10 smaller pieces – each small piece is one-hundredth or 0.01.
4. So 0.35 means 3 tenths and 5 hundredths.

Examples you can see

Let's imagine you're on a space mission to Planet Zog. You need to measure how far your rocket went:

These numbers have a point. The number 2.4 means 2 whole kilometers and 4 tenths of a kilometer. The number 3.6 means 3 whole kilometers and 6 tenths of a kilometer.

Imagine you have 5 alien coins. Each coin is worth £0.25. You have 5 × 0.25 = £1.25 in total. This shows how decimals work with money!

Try it as a mini adventure

Let's go on a space explorer quest!

1. You are on a spaceship and need to collect alien signals. Each signal is worth 0.1 points.
2. On your first day, you collect 3 signals. How many points do you have? 0.3 points
3. On your second day, you collect 5 signals. How many points do you have now? 0.8 points
4. On your third day, you collect 2 signals. What is your total score? 1.0 point
5. On your fourth day, you collect 4 signals. What is your new total? 1.4 points
6. On your fifth day, you collect 7 signals. What is your final score? 2.1 points

You have collected 2.1 points in total. That's a great score for a space explorer!

Common mistakes

• Mistake: Thinking 0.5 is the same as 0.05
  Why it happens: Confusing tenths and hundredths
  Fix: Remember that 0.5 means 5 tenths, and 0.05 means 5 hundredths. Draw a square divided into 100 parts to see the difference.
• Mistake: Adding decimals like 0.3 + 0.4 = 0.7
  Why it happens: Forgetting that 0.3 means 3 tenths and 0.4 means 4 tenths
  Fix: Think of 0.3 + 0.4 as 3 tenths + 4 tenths = 7 tenths = 0.7
• Mistake: Writing 0.1 as 0.10
  Why it happens: Thinking they are different numbers
  Fix: 0.1 and 0.10 are the same! 0.10 means 10 hundredths, which is the same as 1 tenth.

Parent and carer guide

Help your child understand decimals by using everyday examples:

1. Use money: £0.50 is 50p, which is 5 tenths of a pound.
2. Use measuring: A ruler is 10 cm long. 1 cm is 0.1 of a ruler.
3. Use food: Cut a pizza into 10 slices. Each slice is 0.1 of the pizza.
4. Play games: Use dice to make decimal numbers. Roll two dice to make 0.34 or 0.72.
5. Encourage your child to explain how they think about decimals – this helps them learn!

Don't worry if they make mistakes – that's part of learning. Ask questions like "How did you work that out?" to help them think more clearly.

Practice questions

1. What is 0.3 + 0.4? 0.7
2. What is 0.8 - 0.5? 0.3
3. How many tenths are in 0.6? 6
4. How many hundredths are in 0.9? 90
5. Which is bigger: 0.7 or 0.07? 0.7
6. What is 0.25 + 0.10? 0.35
7. What is 1.5 - 0.8? 0.7
8. How many hundredths are in 0.08? 8
9. What is 0.1 + 0.9? 1.0
10. Which is smaller: 0.3 or 0.30? They are the same

FAQ

What are decimals?
Decimals are numbers that show parts of a whole, like 0.5 or 0.25. The point separates the whole number from the parts.

How do I know which is bigger, 0.5 or 0.05?
Look at the first number after the point. 0.5 has 5 tenths, and 0.05 has 5 hundredths. 5 tenths is more than 5 hundredths, so 0.5 is bigger.

Why do we use decimals?
Decimals help us be more precise. When you measure something or count small amounts, decimals give you the exact answer.

Can I use decimals with money?
Yes! £2.50 means 2 pounds and 50 pence. The 0.50 is 50 hundredths of a pound.

How can I practice decimals at home?
Use a ruler, a pizza, or money to practice. Try to make numbers like 0.3, 0.6, and 0.9 with objects or drawings.