To multiply a bigger number, split it into parts that are easy to multiply, multiply every part, then add the answers. 7 × 36 = 7 × 30 + 7 × 6 = 210 + 42 = 252. An area model shows why: the rectangle is split into two smaller rectangles. A number just below a round number can be done as round number minus a bit: 6 × 49 = 6 × 50 − 6 × 1.
Explore this idea with maths tools
Equal groups
3 × 4 = 12
12 ÷ 3 = 4
The same picture shows multiplication and division. Each group must have the same number.
Words to know
- partial product
- the answer to one part of a split multiplication
- area model
- a rectangle split into parts to show a multiplication
Worked examples
7 × 36 = ?
- 1.Split 36 into 30 + 6.
- 2.7 × 30 = 210 and 7 × 6 = 42.
- 3.210 + 42 = 252.
= 252
6 × 49 = ?
- 1.49 = 50 − 1, so 6 × 49 = 6 × 50 − 6 × 1.
- 2.300 − 6 = 294.
= 294
You know 8 × 25 = 200. Use it to work out 8 × 27.
- 1.27 is 2 more than 25, so add 2 groups of 8.
- 2.2 × 8 = 16, and 200 + 16 = 216.
= 216
For parents
Method: Split, multiply each part, add
What to say: How can you split this number? Did you multiply every part?
Common mistakes:
- Multiplies only one part of the split number (or stops at the known or round fact) and forgets the other part.
- Multiplies one part and then adds (or takes away) the other part without multiplying it.
- Treats the tens (or hundreds) digit as ones when multiplying the parts.
- Adjusts the round or known fact in the wrong direction (adds groups that should be taken away, or the reverse).