Recombining numbers

Quick answer

Learning outcome

• You can split a number into tens and ones
• You can recombine tens and ones to make the full number
• You understand that the position of a digit shows its value
• You can use this skill to solve problems with bigger numbers

Why this matters

• Read and write numbers correctly
• Add and subtract numbers more easily
• Understand how big numbers are built up
• Prepare for learning multiplication and division

• Counting money (like 3 ten-pound notes and 4 one-pound coins make £34)
• Reading house numbers (like 123 means 1 hundred, 2 tens, and 3 ones)
• Playing games with dice or cards
• Following directions (like "go 30 steps forward, then 5 steps left")

How it works

1. Look at each digit in the number
2. Identify what each digit's place value is (ones, tens, hundreds, etc.)
3. Write out each part with its value
4. Put all the parts together to make the full number

• The digit 2 is in the tens place, so it means 2 tens = 20
• The digit 4 is in the ones place, so it means 4>
• When we recombine them: 20 + 4 = 24

Examples you can see

• 4 is in the tens place, so 4 tens = 40
• 5 is in the ones place, so 5>
• Recombined: 40 + 5 = 45

• 1 is in the hundreds place, so 1 hundred = 100
• 3 is in the tens place, so 3 tens = 30
• 8 is in the ones place, so 8>
• Recombined: 100 + 30 + 8 = 138

• 2 is in the hundreds place, so 2 hundreds = 200
• 0 is in the tens place, so 0 tens = 0
• 7 is in the ones place, so 7>
• Recombined: 200 + 0 + 7 = 207

Try it as a mini adventure

1. First part: 3 tens and 6 ones
   • 3 tens = 30
   • 6>
   • Combined: 30 + 6 = 36
2. Second part: 2 hundreds and 4 tens
   • 2 hundreds = 200
   • 4 tens = 40
   • Combined: 200 + 40 = 240
3. Final cave number: 36 and 240
   • Wait! The cave number is 240, because 36 is just part of the clue

1. 5 hundreds = 500
2. 3 tens = 30
3. 9>
4. Combined: 500 + 30 + 9 = 539

Common mistakes

• Mistake: Mixing up the place values
  • What happens: A child might think 3 tens = 300 instead of 30
  • How to fix: Use base ten blocks or drawings to show the difference between tens and hundreds
• Mistake: Forgetting that 0 in a number means zero of that place value
  • What happens: A child might think 207 means 27 instead of 200 + 0 + 7
  • How to fix: Practice with the number line or use a place value chart to show that 0 is still a number
• Mistake: Adding the parts in the wrong order
  • What happens: A child might write 5 + 50 + 300 = 355 instead of 300 + 50 + 5 = 355
  • How to fix: Always start with the largest place value and work down
• Mistake: Thinking that 0 doesn't count in a number
  • What happens: A child might think 105 = 15 instead of 100 + 0 + 5
  • How to fix: Explain that 0 is a place holder and still counts as part of the number

Parent and carer guide

• Ask your child to explain how they know which digit is in the tens place
• Use everyday situations like counting money or house numbers
• Ask them to show you how they would split a number into parts
• Encourage them to check their work by adding the parts back together

• Are they mixing up tens and hundreds?
• Do they understand that 0 still counts as a number?
• Are they adding the parts in the right order?
• Do they need to see numbers in a different way (like with blocks or drawings)?

• It's normal for children to make mistakes at first
• Some children learn better with visual aids or hands-on materials
• Don't rush them – it takes time to build this skill
• Every mistake is a learning opportunity

• Use a place value chart with your child
• Count out base ten blocks for different numbers
• Play a game where you say a number and they break it down
• Look at house numbers, car numbers, or prices and break them apart

Practice questions

1. Break down the number 34 and recombine it
2. What is 5 tens and 8 ones as a number?
3. Write 2 hundreds, 6 tens, and 3 ones as a number
4. What number is 400 + 20 + 7?
5. Break down 109 and recombine it

1. 3 tens + 4 + 4 = 34
2. 5 tens = 50, 8 so 58
3. 2 hundreds = 200, 6 tens = 60, 3 so 263
4. 400 + 20 + 7 = 427
5. 1 hundred = 100, 0 tens = 0, 9 so 109

FAQ

What does it mean to recombine numbers?

Recombining numbers means taking apart a number into its parts (like tens and ones) and then putting those parts back together to make the original number.

Why is place value important?

Place value helps us understand how much each digit in a number is worth. It makes it easier to read, write, add, and subtract numbers correctly.

How can I help my child practice place value at home?

You can use everyday situations like counting money, reading house numbers, or playing games with dice. You can also use base ten blocks or draw pictures to show how numbers are made up of tens and ones.

What if my child gets confused between tens and hundreds?

Use visual aids like base ten blocks or drawings. Show that 10 ones make 1 ten, and 10 tens make 1 hundred. Practice with lots of examples and real-life situations.

Can recombining numbers help with bigger numbers?

Yes! Once you understand how to recombine numbers, you can use the same method for larger numbers like 1,000s, 10,000s, and beyond. It's the foundation for understanding all numbers.