原式=125X12X86=125X4X3X2X43=125X4X2X3X43=1000X3X43=129000
(125*12)*86=125*12*86=125*4*3*2*43=(125*4*2)*3*43=1000*129=129000考察:125*8=1000
(125*12)*86=125*4*3*86=500*3*86=1500*86=1500*(90-4)=1500*90-1500*4=135000-6000=129000