Question

11．計算（能簡便的簡便運算）
①$\frac{5}{9}$×$\frac{6}{7}$÷$\frac{5}{6}$                   
②$\frac{5}{4}$÷3+$\frac{2}{3}$×$\frac{1}{4}$
③（$\frac{7}{11}$-$\frac{3}{8}$）×88            
④6.8×$\frac{1}{5}$+$\frac{1}{5}$×3.2．

Answer 1

分析 ①根據(jù)分數(shù)乘法與除法的運算法則約分計算即可．
②先算除法與乘法，再算加法．
③④可根據(jù)乘法分配律計算．

解答 解：①$\frac{5}{9}$×$\frac{6}{7}$÷$\frac{5}{6}$     
=$\frac{5}{9}$×$\frac{6}{7}$×$\frac{6}{5}$
=$\frac{4}{7}$

②$\frac{5}{4}$÷3+$\frac{2}{3}$×$\frac{1}{4}$
=$\frac{5}{12}$+$\frac{2}{12}$
=$\frac{7}{12}$

③（$\frac{7}{11}$-$\frac{3}{8}$）×88  
=$\frac{7}{11}$×88-$\frac{3}{8}$×88  
=56-33
=23

④6.8×$\frac{1}{5}$+$\frac{1}{5}$×3.2
=（6.8+3.2）×$\frac{1}{5}$
=10×$\frac{1}{5}$
=2．

點評 完成本題要注意分析式中數(shù)據(jù)的特點，能簡便計算的要簡便計算．