Practice Questions

52 × 19

= (50 + 2)(20 -1)

= 50 × 20 - 50 × 1 + 2 × 20 - 10 × 2

= 1000 - 50 + 40 - 20

= 970

15 × 8

= (10 + 5) × 8

= 10 × 8 + 5 × 8

= 80 + 40

= 120

Challenger App