Question

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

Answer 1

分析 首先把分数化成小数，3.6×25.4+37.9×6.4，37.9=25.4+12.5，首先根据乘法分配律，然后6.4=8×0.8，根据乘法结合律计算即可．

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．

点评 考查了运算定律与简便运算，四则混合运算．注意运算顺序和运算法则，灵活运用所学的运算定律简便计算．