0.25*39+0.75*27的简便运算

0.25*39+0.75*27的简便运算
0.25*39+0.75*27的简便运算

0.25*39+0.75*27的简便运算
0.25*39+0.75*27
=0.25*3(13+27)
=0.25*3*4*10
=1*30
=30

0.25*39+0.75*27=0.25*39+0.25*3*27=0.25*(39+81)=0.25*120=30

0.25*39+0.75*27=(1-0.75)*39+0.75*27=39-0.75*39+0.75*27=39-2*0.75=37.5

原式=（0.25*3）*（39/3）+0.75*27
=0.75*13+0.75*27
=0.75*（13+27）
=0.75*40
=30

上式=3*13/4+27*3/4=3*（27+13）/4=3*10=30