1.请用简便方法计算下面各题 1)125×(17×8)×4 2)150×40÷50 =125×8×4×17 =150÷50×40 =1000×68 =3×40 =68000 =120 3)50×(2×4)×25 4)7×8×3×125 =(50×2)×(4×25) =(7×3)×(8×125) =100×100 =21×1000 =10000 =21000 5)19999+9999x9999 6)(99x99+99)÷0.99 =10000+9999+9999x9999 =【99x(99+1)】÷0.99 =10000+9999x(9999+1) =(99x100)÷0.99 =100000000 =10000