Question

13．計算：3$\frac{3}{5}$×25$\frac{2}{5}$+6$\frac{2}{5}$×37.9．

Answer 1

分析 首先把分?jǐn)?shù)化成小數(shù)，3.6×25.4+37.9×6.4，37.9=25.4+12.5，首先根據(jù)乘法分配律，然后6.4=8×0.8，根據(jù)乘法結(jié)合律計算即可．

解答 解：3$\frac{3}{5}$×25$\frac{2}{5}$+6$\frac{2}{5}$×37.9
=3.6×25.4+6.4×37.9
=3.6×25.4+6.4×（25.4+12.5）
=3.6×25.4+6.4×25.4+6.4×12.5
=25.4×（3.6+6.4）+6.4×12.5
=25.4×10+12.5×8×0.8
=254+100×0.8
=254+80
=334．

點評 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)算定律簡便計算．