(1.9-1.9*0.9)/2用简便方法怎么做?

题目

(1.9-1.9*0.9)/2用简便方法怎么做?

答案

（1.9-1.9×0.9）÷2
=（1.9×1-1.9×0.9）÷2
=[1.9×(1-0.9)]÷2
=1.9×0.1÷2
=0.19÷2
=0.095