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Column addition

Add three-digit numbers using the column method, with carrying.

Not startedCAMBRIDGE · 3CBSE · IIIIB · PYP-3

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What is column addition?

Column addition means stacking numbers on top of each other. We line up the ones, tens, and hundreds. Then we add each column, starting from the right.

What does carrying mean?

Sometimes a column adds up to 10 or more. We write the ones digit and carry the tens to the next column. Carrying means moving extra value to the left.

Why start from the right?

We start with the ones column because we need to know if we carry. The carried number affects the next column. Always work from right to left.

Writing the carried number

Write the small carried number above the next column. This helps you remember to add it in. Some people call it a little helper number.

Check your answer

After you finish, check that each column makes sense. Did you add the carried number? Does your answer look reasonable?

Worked examples

  1. 1. 245 + 137

    1. Line up the numbers: 245 on top, 137 below.
    2. Ones column: 5 + 7 = 12. Write 2, carry 1.
    3. Tens column: 4 + 3 = 7, plus carried 1 = 8.
    4. Hundreds column: 2 + 1 = 3.
    5. Answer: 382

  2. 2. 478 + 365

    1. Line up: 478 on top, 365 below.
    2. Ones: 8 + 5 = 13. Write 3, carry 1.
    3. Tens: 7 + 6 = 13, plus carried 1 = 14. Write 4, carry 1.
    4. Hundreds: 4 + 3 = 7, plus carried 1 = 8.
    5. Answer: 843

  3. 3. 526 + 298

    1. Line up: 526 on top, 298 below.
    2. Ones: 6 + 8 = 14. Write 4, carry 1.
    3. Tens: 2 + 9 = 11, plus carried 1 = 12. Write 2, carry 1.
    4. Hundreds: 5 + 2 = 7, plus carried 1 = 8.
    5. Answer: 824

Try it yourself

354 + 279

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