1)125 ×(17 × 8)× 4 = 125×8×4×17 =1000×68 =68000 2)375 × 480 + 6250 × 48 =480×(375+625) =480000 3)67 × 21 +18 × 21 + 85 × 79 =21×(67+18)+85×79 =21×85+85×79 =85×(21+79) =8500 4)13 × 99 =13×(100-1) =1300-13 =1287 5)75000 ÷ 125 ÷ 15 =75×1000÷125÷15 =75÷15×1000÷125 =5×8 =40