Tính. a) 417 × 5 + 417 × 2 + 417 ×3 = …………………………………………………… b) 87 × 3 + 87 × 6 + 87 = …………………………………………………………...

a) 417 × 5 + 417 × 2 + 417 ×3 = 417 × (5 + 2 + 3) = 417 × 10 = 4 170

b) 87 × 3 + 87 × 6 + 87 = 87 × (3 + 6 + 1) = 87 × 10 = 870