Alien planet maths quest: money

Quick answer

You can use maths to plan your budget and make smart choices about how to spend your coins on an alien planet – just like you do at home!

Learning outcome

By the end of this page, you will be able to:

• Count and add up different coin values to make a total
• Use subtraction to find out how much money you have left after a purchase
• Compare prices to decide what to buy when you have a limited budget
• Work out how many items you can buy with your coins

Why this matters

When you go shopping, you need to know how much things cost and how much money you have. On an alien planet, the coins might look very different, but the maths is still the same. Learning how to budget your coins helps you make good choices, just like at home!

How it works

Let’s imagine you’ve landed on an alien planet where the coins are shaped like triangles, circles, and stars. Each coin has a different value. You need to:

1. Count how many coins you have
2. Add up their values
3. Decide what to buy
4. Check if you have enough money
5. Work out how much change you get

Let’s start with counting coins and adding them up.

Examples you can see

Imagine you have 3 triangle coins worth 5 coins each, 2 circle coins worth 2 coins each, and 1 star coin worth 10 coins. How much money do you have?

So you have 29 coins in total. Now let’s say you want to buy a snack that costs 12 coins. How many coins will you have left?

29 coins – 12 coins = 17 coins

You’ll have 17 coins left after buying the snack.

Try it as a mini adventure

Imagine you’re on a space mission and you’ve landed on a planet where the shopkeeper sells items in different coin denominations. Your mission is to buy the best items with your coins.

Here’s your mission:

1. You have 20 coins
2. You want to buy 2 star-shaped snacks (each costs 6 coins)
3. You also want to buy 1 triangle-shaped drink (costs 3 coins)
4. You want to know if you have enough money and how much change you’ll get

Let’s solve this step by step:

First, calculate the cost of the snacks:

2 snacks × 6 coins = 12 coins

Then, add the cost of the drink:

12 coins + 3 coins = 15 coins

You spent 15 coins. You started with 20 coins.

20 coins – 15 coins = 5 coins

You’ll have 5 coins left as change!

Common mistakes

• Mistake: Forgetting to count all your coins before spending.
  Why it happens: You might be excited about shopping and forget to check how much you have.
  Fix: Always count your coins first, then spend!
• Mistake: Adding up prices wrong.
  Why it happens: When you add numbers quickly, you might make a mistake.
  Fix: Count carefully or use fingers to help you add!
• Mistake: Thinking you can buy something that costs more than you have.
  Why it happens: You might get excited and forget how much money you have.
  Fix: Always check your total before buying!

Parent and carer guide

Help your child with alien planet maths by:

1. Using real coins or play money to practice counting
2. Playing a shopping game where they set prices and make purchases
3. Letting them plan a small budget for a pretend trip
4. Encouraging them to write down their maths problems
5. Checking that they understand how much change they should get

It’s okay if they make mistakes – that’s how we learn! Just guide them to check their work carefully.

Practice questions

1. You have 10 coins. You buy a snack for 4 coins. How many coins do you have left?
2. You find 3 coins on the ground. You had 7 coins. How many coins do you have now?
3. You have 15 coins. You want to buy 3 items that each cost 4 coins. How much will it cost? How many coins will you have left?
4. You have 25 coins. You spend 18 coins. How much change will you get?
5. You have 8 coins. You want to buy a drink that costs 5 coins. How many coins will you have left?

Answers:

1. 10 – 4 = 6 coins
2. 7 + 3 = 10 coins
3. 3 × 4 = 12 coins; 15 – 12 = 3 coins
4. 25 – 18 = 7 coins
5. 8 – 5 = 3 coins

FAQ

How do I know how much change I should get?

Subtract the cost of what you bought from the amount you paid. For example, if you pay 10 coins for something that costs 7 coins, you should get 3 coins back.

Can I buy something if I don’t have enough coins?

No, you need enough coins to pay for the item. If you don’t have enough, you can’t buy it – but you can choose something cheaper!

Why do I need to know about money?

Knowing how to count and use money helps you make good choices, like what to buy or how to save your coins for something special.

What if I have a lot of different coins?

It helps to group them by value. Count how many of each kind you have, then add them up. It’s like sorting your toys by type!

How can I practice at home?

You can play shop with your toys or use real coins to practice counting and adding. Try making a list of items you want and how much they cost.