Short multiplication made easy. How to multiply a large number by a single digit number.

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Short multiplication can be used to multiply a large number by a single digit number. All you need to do is multiply each digit from the larger number by the single digit number. Start with the units column (number on the right) and work form right to left.

Example 1

Work out 63 × 7

Set out your short multiplication like this:

6  3

×  7

First work out 3 × 7. This gives 21. Put 1 in your answer line and carry the 2 into the next column (put this underneath the answer line)

6  3

×  7

_  1

Next work out 6 × 7 which is 42 and add the 2 onto 42 to give 44.

Since you are on the last number to be multiplied you put both digits in the answer line.

6  3

×  7

441

Example 2

Work out 487 × 8.

Again set out your short multiplication like this:

4 8 7

×    8

First multiply 7 by 8, this gives 56. Put 6 on your answer line and carry the 5 into the next column (put this under the answer line)

4 8 7

×    8

_    6

Next work out 8 times 8 this gives 64. Also don’t forget to add the 5 onto the 64 to give 69. So put the 9 on your answer line and carry 6 into the next column (put this underneath the answer line).

4 8 7

×    8

_ 9 6

Now all you need to do now is multiply your last number by 8. So 4 times 8 is 32, and adding on the 6 underneath gives 38. Since this is the last column to be multiplied both digits can put on the answer line.

4 8 7

×    8

3896

Example 3

A brick has a length of 37cm. If 5 bricks are put in a line, what is the total length of the 5 bricks.

Here you need to work out 64 times 5.

3  7

×  5

First work out 7 × 5. This gives 35. Put 5 in your answer line and carry the 3 into the next column (put this underneath the answer line)

3  7

×  5

_  5

³

Next work out 3 × 5 which is 15 and add the 3 onto 15 to give 18.

Since you are on the last number to be multiplied you put both digits in the answer line.

3  7

×  5

185

So the total length of the 5 bricks is 185 cm.

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