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Maths Adventures

Mermaid maths quest: place value

A story-led junior maths adventure using pearl patterns, shell money and underwater symmetry to decode big numbers by hundreds, tens and ones.

Quick answer

Place value is how we understand the value of each digit in a number based on its position. In a 3-digit number like 345, the 3 is in the hundreds place, the 4 is in the tens place, and the 5 is in the ones place.

Learning outcome

By the end of this page, you will understand how to break down 3-digit numbers into hundreds, tens, and ones, and use this to build and compare big numbers like a mermaid counting pearls. Success signs:
  • You can say what each digit in a 3-digit number represents
  • You can build a 3-digit number from hundreds, tens, and ones
  • You can compare two 3-digit numbers using place value
  • You can solve a simple problem using place value

Why this matters

Understanding place value helps you read and write big numbers, like the number of shells in a treasure chest or the depth of a cave where mermaids live. It’s the key to understanding how numbers work, which helps with addition, subtraction, multiplication, and division later on. In games like Minecraft or Roblox, place value helps you build with blocks, count resources, and understand coordinates.

How it works

Place value is like a system of positions for each digit in a number. In a 3-digit number:
  1. The hundreds place is the first digit from the left
  2. The tens place is the second digit from the left
  3. The ones place is the third digit from the left
Each place is worth 10 times more than the one to its right. So:
  • 1 hundred = 10 tens = 100 ones
  • 1 ten = 10 ones

Examples you can see

Let’s imagine you are a mermaid and you collect shells. You have 234 shells. Let’s break it down:
  • 2 hundreds = 200 shells
  • 3 tens = 30 shells
  • 4 shells
So, 234 = 200 + 30 + 4. Here’s a table to help you see this:
Place Digit Value
Hundreds 2 200
Tens 3 30
Ones 4 4
Let’s try another example: 567 shells.
  • 5 hundreds = 500 shells
  • 6 tens = 60 shells
  • 7 shells
So, 567 = 500 + 60 + 7.

Try it as a mini adventure

Mermaid’s Pearl Hunt You are a mermaid exploring the coral caves. You find a treasure chest with shells and pearls. Your mission is to count them using place value. 1st time: You count 100 shells. How many hundreds do you have? 1 2nd time: You count 20 more shells. How many tens do you have now? 2 3rd time: You count 5 more shells. How many ones do you have? 5 4th time: You put them all together. What number of shells is that? 125 Now, you find another chest with 342 shells. Can you break this down into hundreds, tens, and ones?
  • Hundreds: 3
  • Tens: 4
  • Ones: 2
Can you make a number that is bigger than 342? Try 351. Which is bigger: 342 or 351?
  • Both have 3 hundreds
  • 342 has 4 tens
  • 351 has 5 tens
  • So, 351 is bigger

Common mistakes

  • Mistake: Thinking 123 is the same as 321.
    Why it happens: Confusing the order of digits.
    Fix: Always look at the place value from left to right. 123 = 100 + 20 + 3, but 321 = 300 + 20 + 1.
  • Mistake: Adding hundreds and tens as if they are the same.
    Why it happens: Not understanding that each place is 10 times bigger.
    Fix: Remember: 1 hundred = 10 tens = 100 ones.
  • Mistake: Forgetting that 0 in a place means no value there.
    Why it happens: Thinking 0 is the same as 1.
    Fix: 0 means “nothing” in that place. So 205 = 200 + 0 + 5.

Parent and carer guide

  1. How to help: Use everyday items like coins, pasta, or buttons to build numbers. For example, 234 shells = 2 big cups of 100, 3 small cups of 10, and 4 loose items.
  2. What to say: “Let’s look at the number 456. How many hundreds do we have? How many tens? How many ones?”
  3. What not to worry about: It’s okay if your child counts slowly at first. Focus on understanding the concept, not speed.
  4. Encourage: Let your child explain their thinking. If they say “I have 2 hundreds, 3 tens, and 4 ones,” that’s great!
  5. Play together: Play a game where you give a number and your child builds it with objects or draws it as a picture.

Practice questions

  1. Break down the number 378 into hundreds, tens, and ones.
  2. Which is bigger: 421 or 412?
  3. What number has 5 hundreds, 6 tens, and 3 ones?
  4. How many hundreds, tens, and ones are in 209?
  5. Can you make a number that is between 300 and 400 using 3, 5, and 7?
Answers:
  1. 3 hundreds, 7 tens, 8 ones
  2. 421 is bigger (because 2 tens > 1 ten)
  3. 563
  4. 2 hundreds, 0 tens, 9 ones
  5. 357 or 375 (both are between 300 and 400)

FAQ

What is place value?

Place value is how we know the value of each digit in a number based on where it is placed. Each position is worth 10 times more than the one to its right.

Why do we need to know place value?

Place value helps us understand numbers, compare them, and do maths like addition and subtraction. It’s the foundation for all math you’ll learn later.

How can I practice place value at home?

Use everyday objects like coins, pasta, or buttons. Build numbers with them, or draw pictures of numbers. You can also play games where you guess numbers based on clues like “I have 4 hundreds, 2 tens, and 7 ones.”

What happens if I see a 0 in a number?

A 0 in a place means there are no groups of that size. For example, in 205, there are 0 tens, so the number is 200 + 0 + 5.

Can I use place value with bigger numbers?

Yes! Place value works for any number. After hundreds, there are thousands, ten thousands, and more. But we start with hundreds, tens, and ones to build a strong foundation.