1)125 ×(17 × 8)× 4 = 125×8×4×17 =1000×68 =68000 2)375 × 480 + 6250 × 48 =480×(375+625) =480000 3)25 × 16 ×125 =25×2×8×125 =50000 4)13 × 99 =13×(100-1) =1300-13 =1287 5)75000 ÷ 125 ÷ 15 =75×1000÷125÷15 =75÷15×1000÷125 =5×8 =40