42×125×8×5 =(42x5)x(125x8)=210x1000=21000023×5×2 =23x(5x2)=23x10=23025×9×4 =(25x4)x9=100x9=90015×162×2 =(15x2)x162=30x162=4860(250×125)×(4×8)=(250x4)x(125x8)=1000x1000=1000000供参考。