X Tables
Maths Adventures

Detective maths quest: place value

A story-led junior maths adventure using evidence, charts and mystery patterns to decode big numbers by hundreds, tens and ones.

Quick answer

Place value means understanding how the position of a digit in a number tells us its value. In a 3-digit number like 345, the '3' is worth 300 (hundreds), the '4' is worth 40 (tens), and the '5' is worth 5 (ones). You can solve mysteries by looking at each digit's place value!

Learning outcome

By the end of this page, you will be able to:
  • Identify the hundreds, tens, and ones in any 3-digit number
  • Use place value to solve puzzles and decode mystery numbers
  • Read and write 3-digit numbers in different ways
  • Build and compare 3-digit numbers using place value
Success signs:
  • You can say what each digit in 257 means
  • You can build 3-digit numbers from clues
  • You can compare two 3-digit numbers
  • You can explain how place value helps solve puzzles

Why this matters

Place value is like a detective's clue system. When you see a number like 462, you're not just looking at 4, 6, and 2. Each digit has a special job based on where it stands. This skill helps you:
  • Read big numbers like 1,234 or 5,678
  • Count money in pounds and pence
  • Measure distances in metres and centimetres
  • Play games with scores and points
  • Understand how many things you have in a collection

How it works

Let's think of numbers like a treasure map. Each digit has a special place:
  • The hundreds place is like the first clue on your map
  • The tens place is the second clue
  • The ones place is the final treasure
We can use a place value chart to help us see this clearly:
Hundreds Tens Ones
? ? ?
To understand place value, we need to know:
  1. Each place is worth 10 times more than the one to its right
  2. The digit in each place tells us how many groups of that value we have
  3. We can write numbers in different ways (expanded form, standard form, word form)

Examples you can see

Let's look at the number 247:
Place Digit Value
Hundreds 2 2 × 100 = 200
Tens 4 4 × 10 = 40
Ones 7 7 × 1 = 7
Expanded form: 200 + 40 + 7 Word form: Two hundred and forty-seven Standard form: 247 Real-world example: Imagine you're a detective solving a case. You find a note with the number 389. You need to find out how many clues are hidden:
  • 3 clues in the first room (3 × 100 = 300)
  • 8 clues in the second room (8 × 10 = 80)
  • 9 clues in the final room (9 × 1 = 9)

Try it as a mini adventure

The Mystery of the Missing Numbers You are a detective in the city of Numbersville. The mayor's treasure chest has been broken open, and the numbers inside are scrambled! You must find the real numbers by decoding the clues. Clue 1: The number has 5 hundreds, 2 tens, and 7 ones. Clue 2: The number is less than 600 but more than 400. Clue 3: If you add the hundreds and ones digits, you get 12. Clue 4: The tens digit is half the hundreds digit. What is the number? Solution:
  • Hundreds digit = 5 (from Clue 1)
  • Tens digit = 2 (from Clue 1)
  • Ones digit = 7 (from Clue 1)
  • Check Clue 3: 5 + 7 = 12 ✓
  • Check Clue 4: 2 = 5 ÷ 2 ✓
  • Number = 527
Challenge 2: Detective's Secret Code A secret message says: "The number is 300 + 40 + 9." What is the number? Answer: 349 Challenge 3: The Number Puzzle You found a note that says: "This number is made up of 6 hundreds, 0 tens, and 3 ones." What is the number? Answer: 603

Common mistakes

  • Mistake: Thinking 345 means 3 + 4 + 5 = 12 Why it happens: Confusing place value with simple addition Fix: Remember each digit's position tells its value. 345 = 300 + 40 + 5
  • Mistake: Writing 506 as "five hundred and six" instead of "five hundred and six" Why it happens: Confusing the word "and" with place value Fix: "And" in numbers is used for the decimal point, not between hundreds and tens
  • Mistake: Thinking 1000 is 100 + 10 + 1 Why it happens: Not understanding that place value moves by 10s Fix: 1000 = 1 × 1000, 100 = 1 × 100, 10 = 1 × 10, 1 = 1 × 1

Parent and carer guide

How to help your child at home:
  • Use everyday items like coins, blocks, or beads to build numbers
  • Play the "Place Value Detective" game with your child using house numbers, car numbers, or prices
  • Ask your child to explain how many hundreds, tens, and ones are in a 3-digit number
  • Use a place value chart together to build numbers
  • Practice writing numbers in expanded form (e.g., 456 = 400 + 50 + 6)
What to watch for:
  • Your child mixing up place values (tens and hundreds)
  • Confusing "and" in numbers with place value
  • Difficulty with numbers that have zeros (like 305)
Don't worry if:
  • Your child makes mistakes at first - they're learning!
  • They need to count out blocks or use a chart - that's normal!
  • They're not fluent yet - practice makes progress!

Practice questions

  1. What is the value of the digit 5 in 357?
  2. Write 628 in expanded form
  3. Which number is greater: 456 or 465?
  4. How many hundreds, tens, and ones are in 802?
  5. What is the number that has 7 hundreds, 0 tens, and 9 ones?
Answers:
  1. 50 (because 5 is in the tens place)
  2. 600 + 20 + 8
  3. 465 is greater
  4. 8 hundreds, 0 tens, 2 ones
  5. 709

FAQ

What is place value?

Place value is the value of each digit in a number based on its position. The further left a digit is, the more it's worth.

Why is place value important?

Place value helps us understand numbers, compare them, and do maths with them. It's the foundation for everything from counting to algebra.

How can I help my child learn place value?

Use everyday numbers, play games with place value, build numbers with blocks or coins, and practice writing numbers in different forms.

What comes after hundreds in place value?

After hundreds come thousands, then ten thousands, then hundred thousands, and so on.

Can a number have zeros in place value?

Yes! Zeros are important. For example, in 407, the zero in the tens place tells us there are no tens, but the 4 is worth 400 and the 7 is worth 7.