简便计算。
25 ×4 ×125
35×224×20
= (25 ×4) ×125 = 100 ×125 = 12500
= (35×20)×224 = 700×224 = 156800
128×25 ×8
= 128×(25 ×8) = 128×200 = 25600
125×56 ×80
= (125 ×80)×56 = 10000 ×56 = 560000