Question

Tính nhẩm:

2 x 7 2 x 5 2 x 2

2 x 4 2 x 9 2 x 6

5 x 5 5 x 7 5 x 3

5 x 6 5 x 8 5 x 9

Answer 1

2 x 7 = 14 2 x 5 = 10 2 x 2 = 4

2 x 4 = 8   2 x 9 = 18   2 x 6 = 12

5 x 5 = 25   5 x 7 = 35   5 x 3 = 15

5 x 6 = 30   5 x 8 = 40   5 x 9 = 45