Multiplying and dividing by two digits; divisibility · Usually met around P4
Long multiplication
Split the multiplier into tens and ones.
How to do it
Method
Split the multiplier into tens and ones
34 × 27 = 34 × 20 + 34 × 7 = 680 + 238 = 918
Another way
Column multiplication
34 × 7 = 238, 34 × 20 = 680, 238 + 680 = 918
In full
Split the number you're multiplying by into tens and ones. Multiply by each part, then add. This is the distributive property: 34 × 27 → 34 × 20 = 680, 34 × 7 = 238, 680 + 238 = 918. To multiply by a whole ten, multiply by its tens digit, then put a zero on the end: 34 × 2 = 68, so 34 × 20 = 680. Three digits times two digits works the same way: 215 × 32 → 215 × 30 = 6450, 215 × 2 = 430, 6450 + 430 = 6880. Estimate first to check: 34 × 27 is about 30 × 30 = 900. Another way is to multiply in columns. Multiply by the ones first: 34 × 7 = 238. Then multiply by the tens on a second row: 34 × 20 = 680. Then add the two rows: 238 + 680 = 918.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
32 × 16
Show the answer and working
Answer: 32 × 16 = 512
32 × 16: split 16 into 10 and 6, 32 × 10 = 320, 32 × 6 = 192, 320 + 192 = 512
Example 2
85 × 17
Show the answer and working
Answer: 85 × 17 = 1445
85 × 17: split 17 into 10 and 7, 85 × 10 = 850, 85 × 7 = 595, 850 + 595 = 1445
Example 3
258 × 11
Show the answer and working
Answer: 258 × 11 = 2838
258 × 11: split 11 into 10 and 1, 258 × 10 = 2580, 258 × 1 = 258, 2580 + 258 = 2838
Practise it in the game →Multiplying and dividing by two digits; divisibility · Free to start, unlimited questions, no download