Tính nhẩm 2 × 1 = …. 2 × 3 = ….. 2 × 2 = …… 2 × 5 = …… 2 × 4 = ….

2 × 1 = 2                2 × 3 = 6                2 × 2 = 4                2 × 5 = 10

2 × 4 = 8                2 × 8 = 16              2 × 6 = 12              2 × 9 = 18