Column addition

Column addition is a written method for adding numbers too big to add in your head. Line the numbers up by place value, add one column at a time from the ones, and carry 1 into the next column when a column makes 10 or more.

Key facts

  • Line up the digits by place value: ones under ones, tens under tens (and decimal points under each other).
  • Always start with the ones column, on the right.
  • Adding: if a column makes 10 or more, write the ones digit and carry 1 into the next column.
  • Check: answer − one of the numbers = the other number.
  • Estimate first by rounding each number; if your answer is far from the estimate, check your working.

Worked examples

Example 1

245 + 138

  1. Line up the hundreds, tens and ones.
  2. Add the ones, then the tens, then the hundreds. 245 + 138 = 383

Answer: 383

Example 2

526 + 281

  1. Line up the hundreds, tens and ones.
  2. Add the ones, then the tens, then the hundreds. 526 + 281 = 807

Answer: 807

Example 3

458 + 367

  1. Ones: 8 + 7 = 15. Write 5, carry 1.
  2. Tens: 5 + 6 + 1 = 12. Write 2, carry 1.
  3. Hundreds: 4 + 3 + 1 = 8.
  4. Answer: 825

Answer: 825

Example 4

A stadium has 3,458 seats in the north stand and 2,867 in the south stand. How many seats is that altogether?

  1. Line up the thousands, hundreds, tens and ones.
  2. Add the ones, then the tens, then the hundreds, then the thousands, carrying when a column makes 10 or more. 3,458 + 2,867 = 6,325

Answer: 6,325

Example 5

£23.65 + £8.79

  1. Hundredths: 5 + 9 = 14. Write 4, carry 1.
  2. Tenths: 6 + 7 + 1 = 14. Write 4, carry 1.
  3. Ones: 3 + 8 + 1 = 12. Write 2, carry 1.
  4. Tens: 2 + 1 = 3. Answer: £32.44

Answer: £32.44