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Split and combine: a mental math trick

When to use it: Multiplying a two-digit number by a one-digit number.

Worked example

Split and combine: 7 × 46A 7 by 46 rectangle, cut into 40 and 6: 280 and 42, which add to 322.7467 × 40 = 2807 × 6 = 4240280 + 42 = 322
  1. Split the bigger number into tens and ones.
  2. Multiply each part.
  3. Add the parts.

example 7 × 46

  1. 7 × 40 = 280.
  2. 7 × 6 = 42.
  3. 280 + 42 = 322.

Answer: 322

Try three

  1. 8 × 24

    Show the answer

    192

  2. 9 × 22

    Show the answer

    198

  3. 9 × 52

    Show the answer

    468

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Used in: Bigger multiplication · Division

More mental math tricks

This technique and its worked example are Doing Math’s own lesson text, checked by a blind re-solve and a review on September 27, 2026.