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MathidiaMathematics Academy
Calculations and problem solving
Lesson 12 of 75
Easy practice

Written calculations

Objective. Use reliable written methods for all four operations.

  1. 1. Learn
  2. 2. Worked example
  3. 3. Practice
  4. 4. Feedback
  5. 5. Continue

Learn: the key idea

Written methods are reliable when numbers are too big to work out mentally. Column addition and subtraction line up digits by place value and work from the ones; exchange (carry or borrow) ten when a column goes past 9 or below 0. For example, 735 − 268: exchange to make 15 − 8 = 7, then 12 − 6 = 6, then 6 − 2 = 4, giving 467. Long multiplication and short division follow the same place-value logic.

Worked example

Use a written column calculation to work out 735 − 268.

735 … 268
Illustrated card showing 735 … 268
  1. 1Ones: 5 − 8 cannot be done, so exchange a ten: 15 − 8 = 7.
  2. 2Tens: now 2 − 6 cannot be done, so exchange a hundred: 12 − 6 = 6.
  3. 3Hundreds: now 6 − 2 = 4.
  4. 4735 − 268 = 467. Check: 467 + 268 = 735.

Answer: 467

Concept mastery

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Practice

Practice happens on its own screen, one question at a time. Answers stay hidden until you submit yours, and you can stop and pick up at the same question later.

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Common mistake. A common slip is misaligning the columns, for example putting 268 under 735 one place to the left. Always line up ones under ones, tens under tens, and check with an estimate.

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