Tính nhanh (a) 2 459 – (400 + 459) (b) 435 × 25 + 76 × 435 – 435 (c) 36 × 49 + 51 × 36
Giải thích
a) 2 459 – (400 + 459)
= 2 459 – 400 – 459
= 2 000 – 400
= 1 600
b) 435 × 25 + 76 × 435 – 435
= 435 × 25 + 76 × 435 – 435 × 1
= 435 × (25 + 76 – 1)
= 435 × 100
= 43 500
c) 36 × 49 + 51 × 36
= 36 (49 + 51)
= 36 × 100
= 3 600