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Maths Adventures

Time-travel maths quest: subtraction

A story-led junior maths adventure using clocks, calendars and ancient numbers to work out what is left after trades, rescues or escapes.

Quick answer

Subtraction is like taking away or finding what's left. In a time-travel maths quest, you might need to work out how many minutes are left on a timer, how many dinosaurs are still hiding, or how many coins you have after spending some.

Learning outcome

By the end of this page, you will be able to subtract numbers up to 100 using clocks, calendars, and real-life time-travel scenarios to find out what's left. Success signs:
  • You can count backwards on a clock to find how much time is left
  • You can use a calendar to work out how many days are left until a special event
  • You can solve subtraction problems with numbers up to 100
  • You can act out subtraction problems using toys or drawings

Why this matters

Subtraction helps you figure out how much is left when you take something away. In a time-travel adventure, you'll need subtraction to know how much time you have before your spaceship runs out of fuel, how many treasures are left to collect, or how many friends you still need to rescue. Subtraction is also useful in everyday life for sharing snacks, calculating change, or planning how long a trip will take.

How it works

Subtraction means taking one number away from another to find the difference. When you subtract, you are asking, "What's left?" You can think of subtraction in many ways:
  • Counting backwards
  • Removing objects from a group
  • Using a number line
  • Using a clock to see how much time has passed
When working with time, you can subtract hours and minutes to find how much time is left or how much time has passed. For example, if it's 3 o'clock now and you need to wait 2 hours, you can count backwards from 3 to find out when you'll be ready.

Examples you can see

Let's imagine you're on a time-travel quest and need to solve subtraction problems to escape the past or save the future! Example 1: Clock subtraction It's 4 o'clock now. You need to wait 2 hours to catch your time train. What time will you arrive?
  • Start at 4 o'clock
  • Count backwards 2 hours
  • 4 - 2 = 2
  • You will arrive at 2 o'clock
Example 2: Calendar subtraction Today is Monday, and your birthday party is in 5 days. What day is your party?
  • Start at Monday
  • Count forward 5 days
  • Monday + 5 = Saturday
  • Your party is on Saturday
Example 3: Treasure subtraction You find 10 coins in the past. You spend 3 coins on a magic potion. How many coins do you have left?
  • Start with 10 coins
  • Take away 3 coins
  • 10 - 3 = 7
  • You have 7 coins left

Try it as a mini adventure

Time-Travel Treasure Quest You are a time-traveler on a mission to collect 12 magical crystals. You have already found 5 crystals. How many more crystals do you need to find?
  • Start with 12 crystals
  • You have found 5 crystals
  • 12 - 5 = ?
  • How many more crystals do you need?
Step-by-step challenge:
  • 1st time: You have 12 crystals. You find 3 more. What do you have now? 12 + 3 = 15 crystals
  • 2nd time: You need to give 4 crystals to a friendly time guardian. How many do you have now? 15 - 4 = 11 crystals
  • 3rd time: You see 6 more crystals in a cave. How many crystals do you have now? 11 + 6 = 17 crystals
  • 4th time: You must leave 8 crystals at the time portal. How many crystals do you have left? 17 - 8 = 9 crystals
  • 5th time: You have 9 crystals. You need to collect 3 more. How many do you have now? 9 + 3 = 12 crystals

Common mistakes

  • Mistake: Forgetting to borrow when subtracting larger numbers
    • Why it happens: Children might not understand that they need to take one from the next column when the top number is smaller
    • Fix: Use visual aids like base ten blocks or number lines to show how borrowing works
  • Mistake: Confusing "how many more" with "how many less"
    • Why it happens: The words can sound similar, and children may not understand the difference in meaning
    • Fix: Practice with real objects and ask "how many are left?" and "how many did we take away?"
  • Mistake: Counting forward instead of backwards on a clock
    • Why it happens: Children might be more comfortable counting forward than backwards
    • Fix: Practice counting backwards on a clock and use visual cues like a pointer moving backwards

Parent and carer guide

To help your child with time-travel subtraction, try these 5-minute activities:
  • Use a real clock and ask your child to tell you what time it will be in 5 minutes or 10 minutes
  • Play a game where you hide some toys and ask how many are left
  • Count backwards from 20 to 0 while walking or driving
  • Use a calendar to find out how many days are left until a birthday or holiday
  • Practice with simple subtraction problems using objects like buttons or coins
What to watch for:
  • Your child may mix up counting forwards and backwards
  • They might need extra practice with numbers over 20
  • They might get confused by the language of subtraction
How to help:
  • Use physical objects to demonstrate subtraction
  • Practice counting backwards regularly
  • Make subtraction fun with games and stories
  • Encourage them to explain their thinking

Practice questions

  1. It's 6 o'clock now. You wait 3 hours. What time is it? Answer: 3 o'clock
  2. You have 15 stickers. You give 7 to your friend. How many do you have left? Answer: 8 stickers
  3. Today is Wednesday. What day is it in 4 days? Answer: Sunday
  4. You find 12 seashells. You lose 5 on the way home. How many do you have left? Answer: 7 seashells
  5. It's 10 o'clock. You have to wait 6 hours. What time will you be ready? Answer: 4 o'clock
  6. You collect 20 coins. You spend 8 coins on a time machine part. How many coins do you have left? Answer: 12 coins
  7. Today is Friday. What day was it 3 days ago? Answer: Tuesday
  8. You have 18 balloons. You pop 9 balloons. How many do you have left? Answer: 9 balloons
  9. It's 8 o'clock. You need to wait 4 hours. What time will you be ready? Answer: 4 o'clock
  10. You have 25 candies. You eat 12 candies. How many do you have left? Answer: 13 candies

FAQ

What is subtraction in time-travel maths?

Subtraction in time-travel maths is finding out how much time is left or how much has been taken away when you travel through time. It helps you solve puzzles about how much time you have left or how many items you still need to collect.

How can I practice subtraction with my child?

You can practice by using clocks, calendars, or real objects. Ask questions like "If you have 10 coins and spend 3, how many do you have left?" or "What time will it be in 3 hours?"

Why is subtraction important in time travel?

Subtraction helps time-travelers know how much time they have left, how many items they need to collect, and how much they've used. It's like a math puzzle that helps you solve problems and escape or rescue in time.

Can I use subtraction with large numbers?

Yes! Subtraction works with any numbers, including larger ones. You can subtract 2-digit or 3-digit numbers using the same principles you learn with smaller numbers.

How can I make subtraction fun for my child?

Make it a game! Create time-travel scenarios, use toys or snacks to show subtraction, or play counting games. You can also use stories and adventures to make subtraction feel exciting and meaningful.