0.45+4.5*0.9
=4.5*0.1+4.5*0.9
=4.5*（0.1+0.9）
=4.5*1
=4.5但0.45+4.5*0.9等于4.455啊0.45+4.5*0.9=0.45+4.05=4.5 你怎么算的？