learnbits.app· Geography

Multiplying larger numbers

You learn to multiply a bigger number by partitioning it into tens and ones.

Practise thisWhiteboardMake it a quiz

How to work it out

  1. Split the two-digit number into tens and ones: 67 is 60 and 7.
  2. Multiply tens by the single digit.
  3. Multiply ones by the single digit.
  4. Add the two answers.
3 × 673 × 60=1803 × 7=21180 + 21 = 201

A worked example

3 × 67

  1. Partition 67 into 60 and 7.
  2. Do 3 × 60 = 180.
  3. Do 3 × 7 = 21.
  4. Add them: 180 + 21 = 201.
More examples

28 × 4

  1. Partition 28 into 20 and 8.
  2. Do 4 × 20 = 80.
  3. Do 4 × 8 = 32.
  4. Add them: 80 + 32 = 112.
4 × 284 × 20=804 × 8=3280 + 32 = 112

6 × 23

  1. Partition 23 into 20 and 3.
  2. Do 6 × 20 = 120.
  3. Do 6 × 3 = 18.
  4. Add them: 120 + 18 = 138.

4 × 38

  1. Partition 38 into 30 and 8.
  2. Do 4 × 30 = 120.
  3. Do 4 × 8 = 32.
  4. Add them: 120 + 32 = 152.

Try it yourself

  1. 8 × 26 =

  2. 23 × 6 =

Watch out

  • You multiply only one part: for 3 × 67 you do 3 × 60, add the 7 and say 187.

    Multiply both parts by the small number: 3 × 60 and 3 × 7.

Tips

  • Multiply both parts by the small number.
  • A diagram helps: draw two branches and write the answer under each one.

Why it works

3 × 67 is not in any times table. But you do know 3 × 60 and 3 × 7. Because 67 is exactly 60 and 7, you just add those two answers together. The diagram shows how.