Question

19．脫式計(jì)算．
$\frac{3}{5}$×15×$\frac{2}{9}$
$\frac{2}{3}$×$\frac{5}{4}$×$\frac{9}{10}$
$\frac{10}{21}$×$\frac{12}{25}$×$\frac{7}{8}$
$\frac{3}{20}$×14×$\frac{5}{7}$．

Answer 1

分析 根據(jù)分?jǐn)?shù)乘法的計(jì)算方法和計(jì)算順序進(jìn)行計(jì)算即可．

解答 解：（1）$\frac{3}{5}$×15×$\frac{2}{9}$
=9×$\frac{2}{9}$
=2；

（2）$\frac{2}{3}$×$\frac{5}{4}$×$\frac{9}{10}$
=$\frac{5}{6}×\frac{9}{10}$
=$\frac{3}{4}$；

（3）$\frac{10}{21}$×$\frac{12}{25}$×$\frac{7}{8}$
=$\frac{8}{35}×\frac{7}{8}$
=$\frac{1}{5}$；

（4）$\frac{3}{20}$×14×$\frac{5}{7}$
=$\frac{21}{10}×\frac{5}{7}$
=$\frac{3}{2}$．

點(diǎn)評(píng) 本題主要考查了學(xué)生對(duì)分?jǐn)?shù)乘法計(jì)算方法和計(jì)算順序的掌握．