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addition

Column addition with regrouping

Use place-value exchange to handle sums greater than 9 in a column.

Quick answer

Column addition with regrouping is when you add numbers in columns (like 23 + 18) and need to move extra tens or hundreds to the next column when the sum in any column is more than 9.

Learning outcome

By the end of this page, you will be able to add two or more numbers in columns and regroup when needed, so you can solve bigger addition problems like 45 + 37 or 128 + 94. Success signs:
  • You can line up numbers correctly in columns
  • You can add the numbers in each column from right to left
  • You can regroup when the sum is 10 or more
  • You can solve 2-digit and 3-digit addition problems with regrouping

Why this matters

Column addition with regrouping helps you add big numbers quickly and accurately. You use this in everyday life when you add up your shopping bills, count points in games, or work out how many people are going to a party. It’s also a key skill for more advanced maths like long multiplication and subtraction.

How it works

Adding in columns is like stacking blocks. You line up the numbers by place value (ones under ones, tens under tens, hundreds under hundreds). Then you add each column from right to left. If any column adds up to 10 or more, you need to regroup – that means you move the extra tens or hundreds to the next column on the left. Let’s break it down step by step:
  1. Line up the numbers in columns by place value
  2. Add the ones column first
  3. If the sum is 10 or more, write the ones digit under the ones column and carry the tens digit to the tens column
  4. Add the tens column, including any carried number
  5. Repeat for any other columns (hundreds, thousands, etc.)

Examples you can see

Let’s try 23 + 18 using column addition:
Ones Tens
3 2
+ 8 + 1
11 3
First, add the ones column: 3 + 8 = 11. Since 11 is more than 10, we write 1 in the ones column and carry 1 to the tens column. Next, add the tens column: 2 + 1 + 1 (carried) = 4. So, 23 + 18 = 41. Here’s another example: 45 + 37
Ones Tens
5 4
+ 7 + 3
12 7
5 + 7 = 12. Write 2 in the ones column and carry 1 to the tens column. 4 + 3 + 1 = 8. So, 45 + 37 = 82. Let’s try a 3-digit example: 128 + 94
Ones Tens Hundreds
8 2 1
+ 4 + 9 + 0
12 11 1
8 + 4 = 12. Write 2 in the ones column, carry 1 to the tens. 2 + 9 + 1 = 12. Write 2 in the tens column, carry 1 to the hundreds. 1 + 0 + 1 = 2. So, 128 + 94 = 222.

Try it as a mini adventure

Adventure: The Treasure Hunt You are on a treasure hunt and need to add up the number of coins you find in three chests. Chest 1: 24 coins Chest 2: 37 coins Chest 3: 19 coins How many coins do you have in total? Let’s solve this with column addition:
Ones Tens
4 2
+ 7 + 3
+ 9 + 1
20 6
4 + 7 + 9 = 20. Write 0 in ones column, carry 2 to tens. 2 + 3 + 1 + 2 = 8. So, you found 80 coins in total!

Common mistakes

  • Mistake: Forgetting to carry the extra number to the next column. Why it happens: Kids get excited about adding and forget the regrouping step. Fix: Always write the carried number above the next column and add it in the next step.
  • Mistake: Adding the columns from left to right instead of right to left. Why it happens: Not understanding that place value works from right to left. Fix: Practice lining up numbers and always start from the ones column.
  • Mistake: Not writing the carried number clearly. Why it happens: Kids try to do it in their head without writing. Fix: Always write carried numbers clearly above the next column so you don’t lose track.
  • Mistake: Adding the carried number twice or forgetting to add it at all. Why it happens: Confusion about which numbers to add. Fix: Double-check the carried number is added once in the next column.

Parent and carer guide

Parents and carers can help by:
  • Practising column addition with everyday numbers like the cost of items or the number of toys
  • Using base-10 blocks or counters to show how regrouping works
  • Checking that the child lines up numbers correctly in columns
  • Encouraging the child to say out loud what they are doing, like "I have 7 ones, so I carry 1 to the tens"
  • Being patient and praising effort, not just correct answers
If you notice your child struggling:
  • Use physical objects like coins or counters to show what regrouping means
  • Practice simple 2-digit addition without regrouping first
  • Use number lines or visual aids to help with place value

Practice questions

  1. 56 + 28 = ?
  2. 34 + 47 = ?
  3. 123 + 59 = ?
  4. 89 + 74 = ?
  5. 245 + 187 = ?
Answers:
  1. 84
  2. 81
  3. 182
  4. 163
  5. 432

FAQ

What is column addition with regrouping?

It’s a way to add numbers by writing them in columns and carrying numbers when the sum in any column is more than 9.

Why do we need to regroup?

Because when you add numbers and get 10 or more, you need to move the extra tens to the next column to keep the place value correct.

How do I know when to regroup?

If the sum in any column is 10 or more, you must regroup. Write the ones digit in that column and carry the tens digit to the next column.

Can I use column addition for bigger numbers?

Yes! You can use column addition for any number of digits, including hundreds, thousands, and more.

What if I get confused with carrying?

Write the carried number clearly above the next column. You can also double-check your work by adding again or using a calculator.