# Multiply a two digit number by a small single digit number

Lesson

Did you know that when we multiply a number less than 5 by a two digit number, there are some tips we can use.  This helps us break it into smaller problems.

Think of how we partition numbers, as this can help you understand how to break your two digit number into separate parts.

Imagine if you knew how to solve something like $3x34$3x34  by renaming it as $3x30$3x30 plus $3x4$3x4.

Not only can you do that, you can also rename $3x30$3x30 as $3x3tens$3x3tens which is $9tens,or90$9tens,or90.

You can work out that $3x4=12$3x4=12  and you are ready to solve $90+12$90+12  , which is $102$102.

Watch this video to see some more tips for working out problems like this one.

##### Question 1

Find $1\times31$1×31.

##### Question 2

Find $42\times3$42×3.

##### Question 3

Find $2\times78$2×78.

### Outcomes

#### NA3-6

Record and interpret additive and simple multiplicative strategies, using words, diagrams, and symbols, with an understanding of equality