3.2×0.25×0.125＝4×0.8×0.25×0.125＝(4×0.25)×(0.8×0.125)＝1×0.1＝0.1
＝4×0.8×0.25×0.125＝(4×0.25)×(0.8×0.125)＝1×0.1＝0.1
（0.4乘0.25）乘（0.8乘0.125）
（0.25×0.4）×（0.125×8）=0.1
