Mental mathSplit and combine
Split or combine to make the multiplication easy.
15 × 18 is 15 × 10 plus 15 × 8, and 37 × 6 + 63 × 6 is simply 100 × 6. These free printable worksheets practise the distributive property in both directions — splitting a product apart and combining two into one — for grades 3 to 5.
If they get stuck

The answer key prints on a separate page.
Splitting turns a two-digit multiplication into two easy ones. 15 × 18 becomes 15 × 10 + 15 × 8 = 150 + 120 = 270. The tens part is always a times-ten fact, so the only real work is the ones part and one addition.
Combining runs the same rule backwards, and it is where the property surprises children. 37 × 6 + 63 × 6 has the same 6 in both products, so it is (37 + 63) × 6 = 100 × 6 = 600 — two multiplications that never need doing. The difference works the same way: 86 × 7 − 36 × 7 = 50 × 7 = 350.
45 × 17