Question

3．怎樣簡便就怎樣算．
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運用乘法分配律可簡算，
②運用乘法交換律可簡算，
③④逆用乘法分配律簡算．

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

點評 此題考查小數(shù)四則混合運算順序和靈活運用運算定律，分析數(shù)據(jù)找到正確的計算方法．