楼主是学生?详细转化如下.

27.6*9.9=27.6*(10-0.1)=27.6*10-27.6*0.1=276-2.76=273.24
3.6-72*0.025=3.6*1-3.6*20*0.025=3.6*1-3.6*20*0.025=3.6*1-3.6*0.5=3.6*(1-0.5)=3.6*0.5=1.8