Tính nhẩm: a) 4 × 2 = . . . . . 4 × 7 = . . . . . 4 × 8 = . . . . . 4 × 3 = . . . . . 4 × 6 = . . . . . 4 × 9 = . . . . . 4 × 1 = . . . . . 4 × 4 = . . . . . 4 × 5 = . .
Giải thích
a)
4 × 2 = 8 4 × 7 = 28 | 4 × 8 = 32 4 × 3 = 12 | 4 × 6 = 24 4 × 9 = 36 | 4 × 1 = 4 4 × 4 = 16 | 4 × 5 = 20 4 × 10 = 40 |
b)
24 : 4 = 6 16 : 4 = 4 | 20 : 4 = 5 32 : 4 = 8 | 12 : 4 = 3 8 : 4 = 2 | 40 : 4 = 10 36 : 4 = 9 |