1.25×3.8＝1.25×（3+0.8）＝1.25×3+1.25×0.8＝3.75+1＝4.75
1.25×3.8=1.25×(4-0.2)=1.25×4-1.25×0.2=5-0.25=4.75
1.25×3.8=1.25×4 -1.25x0.2=5 -0.25=4.75
