Question

20．計算下列各題，能簡算的要用簡便方法計算．
①24÷0.2×1.6
②19×2.6+2.6×0.1
③0.21×99+0.21
④88.5÷0.8÷125．

Answer 1

分析 ①從左往右計算即可求解；
②③根據(jù)乘法分配律簡便計算；
④根據(jù)乘法結(jié)合律簡便計算．

解答 解：①24÷0.2×1.6
=120×1.6
=192

②19×2.6+2.6×0.1
=（20-1）×2.6+0.26
=20×2.6-2.6+0.26
=52-2.6+0.26
=49.4+0.26
=49.66

③0.21×99+0.21
=0.21×（99+1）
=0.21×100
=21

④88.5÷0.8÷125
=88.5÷（0.8×125）
=88.5÷100
=0.885

點評 考查了運算定律與簡便運算，四則混合運算．注意運算順序和運算法則，靈活運用所學的運算定律簡便計算．