Question

3．怎样简便就怎样算．
101×0.45
1.25×0.7×0.8
6.1×3.6+3.6×3.9
4.75×99+4.75．

Answer 1

分析 ①运用乘法分配律可简算，
②运用乘法交换律可简算，
③④逆用乘法分配律简算．

解答 解：①101×0.45
=（100+1）×0.45
=100×0.45+0.45
=45+0.45
=45.45

②1.25×0.7×0.8
=1.25×0.8×0.7
=1×0.7
=0.7

③6.1×3.6+3.6×3.9
=3.6×（6.1+3.9）
=3.6×10
=36

④4.75×99+4.75
=4.75×（99+1）
=4.75×100
=475

点评 此题考查小数四则混合运算顺序和灵活运用运算定律，分析数据找到正确的计算方法．