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How do I multiply two-digit numbers more easily?

Part of Maths and NumeracyNumbers and number processes

Snoot and Fin partition two digit numbers to make multiplying them easier.

How can you multiply by two-digit numbers?

Can you multiply by two-digit numbers like 14 or 37?

It looks a bit difficult, doesn't it? It can be easier if you partition the number into two parts. Instead of multiplying by 29 you can multiply by 20 and then multiply by 9 separately and then add the answers together.

Instead of multiplying by 34 you can multiply by 30 and then multiply by 4 separately and then add the answers together.

Example

3 x 34 = ?

Split the 34 into 30 and 4.

3 x 30 = 90

3 x 4 = 12

Then add these together

90 + 12 = 102

Another strategy is to multiply by a near number that is easier to work with and then add or take away the difference.

Example

6 x 29 = ?

It might be easier to do this as 6 x 30 = 180

Then you need to take away 6 x 1 (because 29 is 30 - 1)

6 x 1 = 6

180 - 6 = 172

Was that easier? Why not try these strategies again next time you have to multiply by two-digit numbers.

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