巧算：0.747*0.25+0.53*0.025-2.5*0.
问题描述：
巧算：0.747*0.25+0.53*0.025-2.5*0.
答
0.747*0.25+0.53*0.025-2.5*0.04
=0.747×0.25+0.053×0.25-0.25×0.4
=0.25×（0.747+0.053-0.4）
=0.25×0.4
=1/4×0.4
=0.1