Column addition and subtraction: what children learn
Year 3 pupils add and subtract numbers with up to three digits, using formal written methods of columnar addition and subtraction.
In this game children work out three-digit additions and subtractions. Many of the questions need an exchange, carrying a ten or a hundred in addition, or exchanging one in subtraction, which is where most mistakes happen.
This topic covers the Year 3 statutory requirement in the National Curriculum in England (Number – addition and subtraction): pupils should be taught to “add and subtract numbers with up to 3 digits, using formal written methods of columnar addition and subtraction”. Year 3 pupils are usually aged 7–8.
For families following US standards, the closest Common Core standard is 2.NBT.B.7, which is taught in Grade 2.
How to play
Answer 10 questions before the clock runs out. Tap an answer, or press 1 to 4. Each game has 10 multiple-choice questions and a 150-second timer. A wrong answer shows the correct one before moving on. You earn up to three stars depending on your score.
Step by step
- Line up the digits. Write hundreds under hundreds, tens under tens and ones under ones.
- Start with the ones. Always work from the right-hand column.
- Carry in addition. If a column adds to 10 or more, write the ones digit and carry the ten into the next column.
- Exchange in subtraction. If the top digit is smaller, exchange one from the next column: one ten becomes ten ones.
Worked examples
Example 1: 631 + 295
Working: Ones: 1 + 5 = 6. Tens: 3 + 9 = 12, write 2, carry 1. Hundreds: 6 + 2 + 1 = 9.
Answer: 926
Example 2: 463 − 328
Working: Ones: 3 − 8 needs an exchange, so 13 − 8 = 5. Tens: 5 − 2 = 3. Hundreds: 4 − 3 = 1.
Answer: 135
Example 3: 704 − 444
Working: Ones: 4 − 4 = 0. Tens: 0 − 4 needs an exchange from the hundreds: 10 − 4 = 6. Hundreds: 6 − 4 = 2.
Answer: 260
Common mistakes and how to fix them
- Subtracting the smaller digit from the larger one in each column, so 463 − 328 = 145. Always take the bottom digit from the top digit, exchanging when you need to.
- Forgetting to add the carried digit. Write the carried 1 clearly under the next column and add it in.
- Lining up digits from the left. Line up from the right so ones are under ones.
Activities to try at home
- Add up prices on a receipt with a written method.
- Find the difference between two page numbers in a book.
- Check each answer with the inverse: add back what you subtracted.
Ideas for the classroom
- Pupils model exchanges with base-ten blocks before writing them.
- Give a calculation with an error and ask pupils to find and fix it.
- Pupils estimate before calculating and compare the estimate with the answer.
Free printable game and worksheet
The free printable starts with a game sheet, such as a colour-by-answer picture, an answer maze or a secret-code joke, followed by a worksheet. Both use the same checked questions as the online game, and the answers are on the last page. Print it, or save it as a PDF from your browser’s print menu.
Open the free printable game and worksheet
Frequently asked questions
Why learn column methods if we have calculators?
Written methods build understanding of place value and help children check whether an answer makes sense.
What is the difference between carrying and exchanging?
They are the same idea: ten in one column is worth one in the next column to the left.
Can it be played with a keyboard?
Yes. Press 1, 2, 3 or 4 to choose an answer.