Stage 6 · Big numbers & speed
×5 by halving
×5 is ×10, then halve.
How to do it
Method
×5 is ×10, then halve
48 × 5 = 480 ÷ 2 = 240
Another way
Column multiplication
Ones 8 × 5 = 40, write 0, carry 4; tens 4 × 5 + 4 = 24 → 240
In full
×5 is ×10 halved. 48 × 5 → 480 → 240; odd numbers too: 37 × 5 → 370 → 185. The same idea: ×50 is ×100 halved, ×25 is ×100 quartered. You can also multiply in columns; the answer is the same.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
15 × 5
Show the answer and working
Answer: 15 × 5 = 75
15 × 5: ×5 is ×10 then halved, 15 × 10 = 150, 150 ÷ 2 = 75
Example 2
31 × 5
Show the answer and working
Answer: 31 × 5 = 155
31 × 5: ×5 is ×10 then halved, 31 × 10 = 310, 310 ÷ 2 = 155
Example 3
28 × 5
Show the answer and working
Answer: 28 × 5 = 140
28 × 5: ×5 is ×10 then halved, 28 × 10 = 280, 280 ÷ 2 = 140
Example 4
92 × 5
Show the answer and working
Answer: 92 × 5 = 460
92 × 5: ×5 is ×10 then halved, 92 × 10 = 920, 920 ÷ 2 = 460
Practise ×5 by halving in the game →Stage 6 · Big numbers & speed · Free to start, unlimited questions, no download