问题
解答题
下面各题怎样简便就怎样算．
①0.25×1.58×4
②18.5×0.8-8.5×0.8
③3.6÷[（17.3+30.7）×0.25]
④4.9÷25÷0.4．
答案
①0.25×1.58×4
=（0.25×4）×1.58
=1×1.58
=1.58
②18.5×0.8-8.5×0.8
=（18.5-8.5）×0.8
=10×0.8
=8
③3.6÷[（17.3+30.7）×0.25]
=3.6÷[48×0.25]
=3.6÷[12×（4×0.25）]
=3.6÷[12×1]
=3.6÷12
=0.3
④4.9÷25÷0.4
=4.9÷（25×0.4）
=4.9÷10
=0.49