一、口算。
$\frac {9}{10}×\frac {5}{6}=$ $\frac {5}{8}+\frac {1}{4}=$ $\frac {1}{100}÷\frac {1}{10}=$
$\frac {3}{4}÷12=$ $10÷\frac {3}{4}=$ $\frac {2}{5}÷\frac {3}{20}=$
$3-\frac {1}{3}=$ $\frac {3}{4}×\frac {5}{6}=$ $\frac {1}{3}÷3=$
$\frac {6}{7}÷2=$ $\frac {3}{8}÷\frac {9}{16}=$ $\frac {5}{6}×\frac {14}{15}=$
$\frac {3}{7}×\frac {1}{6}=$ $\frac {9}{10}-\frac {2}{5}=$ $\frac {8}{27}÷\frac {2}{3}=$
$\frac {4}{5}÷\frac {8}{15}=$ $\frac {6}{11}×66=$ $\frac {4}{5}+\frac {1}{4}=$
$14×\frac {2}{21}=$ $\frac {5}{6}-\frac {4}{9}=$ $\frac {25}{32}×\frac {2}{5}=$

一、$\frac{3}{4}$ $\frac{7}{8}$ $\frac{1}{10}$ $\frac{1}{16}$ $\frac{40}{3}$ $\frac{8}{3}$ $2\frac{2}{3}$ $\frac{5}{8}$ $\frac{1}{9}$ $\frac{3}{7}$ $\frac{2}{3}$ $\frac{7}{9}$ $\frac{1}{14}$ $\frac{1}{2}$ $\frac{4}{9}$ $\frac{3}{2}$ 36 $\frac{21}{20}$ $\frac{4}{3}$ $\frac{7}{18}$ $\frac{5}{16}$

二、计算下面各题。
$\frac {5}{9}÷\frac {2}{3}×\frac {4}{15}$ $\frac {1}{4}÷\frac {2}{3}÷\frac {4}{5}$ $\frac {6}{11}×\frac {4}{3}÷\frac {8}{33}$
$\frac {9}{32}÷\frac {12}{7}÷\frac {7}{16}$ $\frac {12}{25}÷\frac {7}{3}×\frac {5}{9}$ $\frac {14}{31}÷\frac {4}{3}÷\frac {7}{62}$

二、$\frac{2}{9}$ $\frac{15}{32}$ 3 $\frac{3}{8}$ $\frac{4}{35}$ 3

$\frac{5}{9}÷\frac{2}{3}×\frac{4}{15}$
$=\frac{5}{9}×\frac{3}{2}×\frac{4}{15}$
$=\frac{5×3×4}{9×2×15}$
$=\frac{60}{270}$
$=\frac{2}{9}$
$\frac{1}{4}÷\frac{2}{3}÷\frac{4}{5}$
$=\frac{1}{4}×\frac{3}{2}×\frac{5}{4}$
$=\frac{1×3×5}{4×2×4}$
$=\frac{15}{32}$
$\frac{6}{11}×\frac{4}{3}÷\frac{8}{33}$
$=\frac{6}{11}×\frac{4}{3}×\frac{33}{8}$
$=\frac{6×4×33}{11×3×8}$
$=\frac{792}{264}$
$=3$
$\frac{9}{32}÷\frac{12}{7}÷\frac{7}{16}$
$=\frac{9}{32}×\frac{7}{12}×\frac{16}{7}$
$=\frac{9×7×16}{32×12×7}$
$=\frac{1008}{3360}$
$=\frac{3}{8}$
$\frac{12}{25}÷\frac{7}{3}×\frac{5}{9}$
$=\frac{12}{25}×\frac{3}{7}×\frac{5}{9}$
$=\frac{12×3×5}{25×7×9}$
$=\frac{180}{1575}$
$=\frac{4}{35}$
$\frac{14}{31}÷\frac{4}{3}÷\frac{7}{62}$
$=\frac{14}{31}×\frac{3}{4}×\frac{62}{7}$
$=\frac{14×3×62}{31×4×7}$
$=\frac{2604}{868}$
$=3$