Multiplying by a one-digit number · Usually met around P3
Two-digit × one-digit
Split into tens and ones, multiply, add.
How to do it
Method
Split into tens and ones, multiply, add
34 × 7 = 30 × 7 + 4 × 7 = 210 + 28 = 238
Another way
Column multiplication
Ones 4 × 7 = 28, write 8, carry 2; tens 3 × 7 + 2 = 23 → 238
In full
Split the number into tens and ones, multiply each part, then add. 34 × 7 → 30×7=210, 4×7=28, total 238. This is the distributive property, and it's the backbone of all long multiplication. Column multiplication does the same thing, starting from the ones.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
31 × 3
Show the answer and working
Answer: 31 × 3 = 93
31 × 3: split 31 into 30 and 1, 30 × 3 = 90, 1 × 3 = 3, 90 + 3 = 93
Example 2
16 × 3
Show the answer and working
Answer: 16 × 3 = 48
16 × 3: split 16 into 10 and 6, 10 × 3 = 30, 6 × 3 = 18, 30 + 18 = 48
Example 3
19 × 9
Show the answer and working
Answer: 19 × 9 = 171
19 × 9: split 19 into 10 and 9, 10 × 9 = 90, 9 × 9 = 81, 90 + 81 = 171
Practise it in the game →Multiplying by a one-digit number · Free to start, unlimited questions, no download