Question

6．簡(jiǎn)算．
20×$\frac{11}{21}$              
12.5-$\frac{5}{6}$-$\frac{1}{6}$              
32×1.5+3.2×85
3.4×（1.6+1.6+1.6+1.6）×25．

Answer 1

分析 ①把20寫成21-1，根據(jù)乘法分配律進(jìn)行計(jì)算；
②根據(jù)減法性質(zhì)進(jìn)行計(jì)算；
③把32×1.5寫成3.2×15，再根據(jù)乘法分配律進(jìn)行計(jì)算；
④1.6+1.6+1.6+1.6=1.6×4，根據(jù)乘法結(jié)合律計(jì)算．

解答 解：①20×$\frac{11}{21}$   
=（21-1）×$\frac{11}{21}$ 
=21×$\frac{11}{21}$-$\frac{11}{21}$
=11-$\frac{11}{21}$
=10$\frac{10}{21}$ 
          
②12.5-$\frac{5}{6}$-$\frac{1}{6}$      
=12.5-（$\frac{5}{6}$+$\frac{1}{6}$） 
=12.5-1
=11.5
          
③32×1.5+3.2×85
=3.2×15+3.2×85
=3.2×（15+85）
=3.2×100
=320

④3.4×（1.6+1.6+1.6+1.6）×25
=3.4×1.6×4×25
=3.4×120
=408

點(diǎn)評(píng) 完成本題要注意分析式中數(shù)據(jù)，運(yùn)用合適的簡(jiǎn)便方法計(jì)算．