Tính nhanh a) 4 × 126 × 25 b) (9 × 8 – 12 – 5 × 12) × (1 + 2 + 3 + 4 + 5)
Giải thích
a) 4 × 126 × 25
= (4 × 25) × 126
= 100 × 126
= 12 600
b) (9 × 8 – 12 - 5×12) × (1 + 2 + 3 + 4 +5)
= (72 – 12 – 60) × (1 + 2 + 3 + 4 + 5)
= 0 × (1 + 2 + 3 + 4 + 5)
= 0