Question

Find the product using suitable property:
(a) 205 × 1989
(b) 1991 × 1005
(3 marks)

Answer 1

These two parts can be solved using the distributive property. (1 mark)

We can break the first one into 205 × (2000 - 11), so it will simplify our calculations.


205 × (2000 - 11)
= 205 × 2000 - 205 × 11
= 410000 - 2255
= 407745 (1 mark)

Let us look at the second part now, we can split that also into 1991 × (1000 + 5)


1991 × (1000 + 5)
= 1991 × 1000 + 1991 × 5
= 1991000 + 9955
= 2000955 (1 mark)