Question

18．用簡便方法計(jì)算
4-$\frac{4}{5}$÷4-$\frac{4}{5}$；                      6.28×3.7+6.28×6.3．

Answer 1

分析 ①除以4等于乘$\frac{1}{4}$，再根據(jù)減法的性質(zhì)計(jì)算；
②根據(jù)乘法分配律簡便計(jì)算．

解答 解：①4-$\frac{4}{5}$÷4-$\frac{4}{5}$
=4-$\frac{4}{5}$×$\frac{1}{4}$-$\frac{4}{5}$
=4-（$\frac{1}{5}$+$\frac{4}{5}$）
=4-1
=3

②6.28×3.7+6.28×6.3
=6.28×（3.7+6.3）
=6.28×10
=62.8

點(diǎn)評 考查了運(yùn)算定律與簡便運(yùn)算，四則混合運(yùn)算．注意運(yùn)算順序和運(yùn)算法則，靈活運(yùn)用所學(xué)的運(yùn)算律簡便計(jì)算．