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Maths Adventures

Robot maths quest: decimals

A story-led junior maths adventure using circuits, commands and machine logic to measure small distances, money and scores with tenths and hundredths.

Quick answer

Decimals are numbers that are smaller than one whole, like 0.5 or 0.25. In a robot maths quest, decimals help robots measure tiny distances, count small amounts of money, and track scores with tenths and hundredths.

Learning outcome

By the end of this page, you will be able to understand and use decimals in real-life robot adventures, including measuring small distances, counting money, and tracking scores with tenths and hundredths. Success signs:
  • You can show 0.5 as half of a whole object
  • You can compare 0.3 and 0.7 to see which is bigger
  • You can add 0.2 + 0.4 to get 0.6
  • You can use decimals to count money like £1.25

Why this matters

Decimals are used everywhere in robot adventures and real life. Robots need to measure small distances to move precisely, count money to pay for parts, and track scores to win games. Understanding decimals helps you solve problems with tiny amounts, just like robots do. When you understand decimals, you can make robots move exactly where you want, count your pocket money accurately, and know how much of a cake is left.

How it works

Decimals are numbers that are less than one whole. Think of a whole pizza cut into 10 equal pieces. Each piece is one-tenth, or 0.1 of the pizza. If you eat 3 pieces, you have eaten 0.3 of the pizza. The decimal point separates the whole number from the parts. Before the decimal point is the whole number (like 1, 2, 3), and after the decimal point are the parts (like 0.1, 0.2, 0.3).

Examples you can see

Let's imagine you are a robot explorer in a space station. Your mission is to collect small parts for your robot friends. Here are some real examples: Example 1: Measuring distances Your robot needs to move exactly 0.5 metres forward to reach the storage room. If you move 0.3 metres, how much more do you need to move?
  • 0.5 - 0.3 = 0.2 metres
Example 2: Counting money You find 50p in the space station. You spend 0.25p on a snack. How much money do you have left?
  • 0.50 - 0.25 = 0.25p
Example 3: Tracking scores In a robot soccer game, you score 0.7 of a goal. Your friend scores 0.4 of a goal. Who scored more?
  • 0.7 > 0.4, so you scored more

Try it as a mini adventure

Robot Explorer Mission You are a robot explorer in a space station. You have a mission to collect parts for your robot friends. You must use decimals to measure distances, count money, and track scores. Step 1: You need to move 0.8 metres to get to the part storage. You have already moved 0.3 metres. How much further do you need to go?
  • 0.8 - 0.3 = ?
Step 2: You find 50p in the station. You spend 0.25p on a snack. How much money do you have left?
  • 0.50 - 0.25 = ?
Step 3: In a robot race, you finish 0.6 seconds behind the winner. Your friend finishes 0.4 seconds behind. Who was faster?
  • 0.4 seconds is less than 0.6 seconds, so your friend was faster
Step 4: You collect 3 parts that each cost 0.25p. How much did you spend in total?
  • 3 × 0.25 = ?

Common mistakes

  • Mistake: Thinking 0.5 is bigger than 0.7 because 5 is bigger than 7
    Why it happens: Looking at the numbers after the decimal point without understanding their value
    Fix: Remember that 0.5 means 5 tenths and 0.7 means 7 tenths, so 0.7 is bigger
  • Mistake: Adding 0.3 + 0.4 = 0.7 instead of 0.7
    Why it happens: Not lining up the decimal points properly
    Fix: Write the decimal points in line and add the tenths: 3 tenths + 4 tenths = 7 tenths
  • Mistake: Thinking 0.1 is the same as 1
    Why it happens: Confusing tenths with whole numbers
    Fix: Remember that 0.1 is one-tenth, which is much smaller than 1

Parent and carer guide

Parents and carers can help by:
  • Using everyday situations to practice decimals: "If we have 10p and spend 3p, how much do we have left?"
  • Using visual aids like coins, rulers, or measuring cups to show decimal parts
  • Playing games that involve counting money or measuring distances
  • Encouraging children to explain their thinking when solving decimal problems
  • Practicing with real examples like recipes or shopping

Practice questions

  1. What is 0.4 + 0.3?
  2. Which is bigger: 0.6 or 0.9?
  3. How much is 5 × 0.2?
  4. What is 0.8 - 0.5?
  5. What is 0.1 + 0.9?
Answers:
  1. 0.7
  2. 0.9
  3. 1.0
  4. 0.3
  5. 1.0

FAQ

What are decimals?

Decimals are numbers that are less than one whole. They use a decimal point to show parts of a whole, like 0.5 which means 5 tenths.

How do I add decimals?

To add decimals, line up the decimal points and add the tenths together. For example, 0.3 + 0.4 = 0.7.

Why do we use decimals?

We use decimals to measure small amounts, count money, and track scores when we need to be more precise than whole numbers.

How are decimals used in robots?

Robots use decimals to measure small distances, count money for parts, and track scores in games. This helps them be more precise in their actions.

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.