Submarine maths quest: place value

Quick answer

By diving deep into a submarine adventure, you'll learn how to break big numbers into hundreds, tens, and ones – that's place value!

Learning outcome

By the end of this page, you will be able to split any number into hundreds, tens, and ones, and use this to understand how big numbers work.

• You can show a number like 347 as 3 hundreds, 4 tens, and 7 ones.
• You can compare numbers by looking at how many hundreds, tens, and ones they have.
• You can add and subtract numbers using hundreds, tens, and ones.
• You can solve puzzles by finding numbers hidden in the depths of a submarine.

Why this matters

Understanding place value helps you read, write, and work with big numbers – just like how a submarine dives deep to find treasures. It's used in everyday life when you count money, measure things, or even play games. In school, it's the foundation for adding, subtracting, multiplying, and dividing bigger numbers.

How it works

Place value is about how the position of a digit tells you its value. Think of a submarine diving deeper – the deeper you go, the more important each number becomes.

1. Start from the right with the ones place.
2. Then move to the tens place (next to the ones).
3. Then to the hundreds place (next to the tens).
4. For bigger numbers, there are thousands, ten thousands, and even more!

Each place is ten times bigger than the one before it. So, in the number 347:

• The 7 is in the ones place – it means 7 ones.
• The 4 is in the tens place – it means 4 tens, or 40.
• The 3 is in the hundreds place – it means 3 hundreds, or 300.

Examples you can see

Imagine you're on a submarine mission. You dive down to a depth of 347 metres. How can you break this number apart?

So, 347 = 300 + 40 + 7

Let's try another number – 562. What's in each place?

So, 562 = 500 + 60 + 2

You can also use base ten blocks or drawings to show this:

• Each big cube = 100 (hundreds)
• Each long stick = 10 (tens)
• Each small cube = 1 (ones)

Draw 3 big cubes, 4 long sticks, and 7 small cubes to show 347.

Try it as a mini adventure

Imagine you're a young marine explorer on a submarine mission. Your captain gives you a treasure map with hidden coordinates. The coordinates are in the form of numbers. You must find the number that matches the depth of each underwater cave.

1. First cave is at 205 metres. How many hundreds, tens, and ones?
2. Second cave is at 470 metres. How many hundreds, tens, and ones?
3. Third cave is at 603 metres. How many hundreds, tens, and ones?
4. Fourth cave is at 1000 metres. What's the number in hundreds, tens, and ones?

Can you write the numbers in expanded form (like 347 = 300 + 40 + 7)?

Common mistakes

• Mistake: Thinking 500 is 5 hundreds, 0 tens, 0 ones, but not writing it correctly.
  Why it happens: Confusion about the zeros in place value.
  Fix: Remember that 500 = 5 hundreds, 0 tens, 0 ones – the zeros are still important!
• Mistake: Counting from left to right instead of right to left when reading place value.
  Why it happens: Not understanding that the rightmost digit is the smallest place.
  Fix: Always start from the ones place and move left to get bigger values.
• Mistake: Writing 123 as 100 + 20 + 30 instead of 100 + 20 + 3.
  Why it happens: Mixing up the value of the tens digit.
  Fix: Remember that the tens digit stands for how many tens – so 2 tens = 20.

Parent and carer guide

Help your child understand place value by:

• Using everyday numbers like house numbers, prices, or ages to break apart.
• Playing with base ten blocks or drawing hundreds, tens, and ones.
• Practising writing numbers in expanded form (like 234 = 200 + 30 + 4).
• Reinforcing that the position of a digit changes its value.
• Noticing when they make errors – gently guide them to correct it.

Try this: ask your child to build a number like 456 using base ten blocks or drawings. Then ask them to write it in expanded form. This builds confidence and understanding.

Practice questions

1. Break down the number 327 into hundreds, tens, and ones.
2. Write 609 in expanded form.
3. Which number is greater: 456 or 465? Explain using place value.
4. What is 200 + 30 + 5 written as a number?
5. How many hundreds, tens, and ones are in 780?

Answers:

1. 3 hundreds, 2 tens, 7 ones
2. 600 + 0 + 9
3. 465 is greater because it has 6 tens, which is more than 5 tens.
4. 235
5. 7 hundreds, 8 tens, 0 ones

FAQ

What is place value?

Place value means the value of a digit based on where it is in a number. The rightmost digit is the ones place, then tens, then hundreds, and so on.

Why is place value important?

Place value helps you understand how numbers work, which is essential for adding, subtracting, multiplying, and dividing bigger numbers.

How can I practice place value at home?

You can use everyday items like coins, blocks, or even your fingers to show hundreds, tens, and ones. Try writing numbers in expanded form or playing games with place value cards.

What if my child gets confused with zeros?

It’s normal! Remind them that zeros still count. For example, 500 means 5 hundreds, 0 tens, and 0 ones. Use base ten blocks to show this visually.

Can I use this for older children too?

Yes! Place value is foundational. For older children, you can extend it to thousands, ten thousands, and decimals. It's a strong base for future maths learning.