Multiplying by a one-digit number · Usually met around P3
Multiplying three numbers
Multiply the easy pair first.
How to do it
Method
Multiply the easy pair first
4 × 3 × 5 = 4 × 5 × 3 = 20 × 3 = 60
Another way
Left to right
4 × 3 = 12, 12 × 5 = 60
In full
To multiply three numbers, you can go from left to right: 4 × 3 × 5 → 4 × 3 = 12, then 12 × 5 = 60. You can also change the order, or multiply any two first: the product stays the same. So look for an easy pair: 4 × 3 × 5 → 4 × 5 = 20 first, then 20 × 3 = 60, which is quicker. 5 times an even number, and 25 × 4, give whole tens or hundreds. To check, multiply again in another order.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
5 × 8 × 7 = □
Show the answer and working
Answer: 280
Left to right: 5 × 8 = 40, 40 × 7 = 280.
Example 2
4 × 2 × 7 = □ × 7 = □
Fill in each box
Show the answer and working
Answer: 8，56
First 4 × 2 = 8, then 8 × 7 = 56.
Example 3
7 × 3 × 4 = 7 × 12
True or false?
Show the answer and working
Answer: True
You can do 3 × 4 = 12 first, so 7 × 3 × 4 = 7 × 12.
Practise it in the game →Multiplying by a one-digit number · Free to start, unlimited questions, no download