Tính nhẩm: a) 9 × 2 = . . . . . 9 × 4 = . . . . . 9 × 3 = . . . . . 9 × 5 = . . . . . 9 × 8 = . . . . . 9 × 9 = . . . . . 9 × 1 = . . . . . 9 × 6 = . . . . . 9 × 7 = . . . . . 9 × 10 = . . .
Giải thích
a)
9 × 2 = 18 9 × 4 = 36 | 9 × 3 = 27 9 × 5 = 45 | 9 × 8 = 72 9 × 9 = 81 | 9 × 1 = 9 9 × 6 = 54 | 9 × 7 = 63 9 × 10 = 90 |
b)
18 : 9 = 2 27 : 9 = 3 9 : 9 = 1 | 36 : 9 = 4 45 : 9 = 5 90 : 9 = 10 | 72 : 9 = 8 54 : 9 = 6 81 : 9 = 9 |