125×(17×8)×4 =125×8×4×17 =1000×68 =68000 375×480+6250×48 =480×(375+625) =480×1000 =480000 25×16×125 =25×2×8×125 =50×1000 =50000 13×99 =13×(100-1) =1300-13 =1287 75000÷125÷15 =75×1000÷125÷15 =75÷15×1000÷125 =40