原式=3x24x125=3x3x8x125=9x1000=9000
7500
=24×3×125=8×3×3×125=(8×125)×9=1000×9=9000
(24+24+24)x125=24x3x125=8x3x3x125=8x125x(3x3)=1000x9=9000