1.28*1.29-0.29*0.28＝(1+0.28)*(1+0.29)-0.29*0.28＝1+0.29+0.28+0.28*0.29-0.29*0.28＝1.57
利用乘法分配律，原式=（1+0.28）×（1+0.29）-0.29×0.28=1×1+1×0.29+1×0.28+0.28×0.29-0.29+0.28=1+0.29+0.28=1.57
