一、口算。
$\frac {3}{5}×10=$
$\frac {8}{9}×1.5=$
$81×\frac {7}{9}=$
$\frac {2}{3}+\frac {3}{4}=$
$\frac {7}{8}-\frac {3}{4}=$
$\frac {5}{7}×\frac {7}{10}=$
$42×\frac {5}{6}=$
$\frac {7}{32}×\frac {4}{7}=$
$\frac {5}{2}-\frac {2}{5}=$
$\frac {1}{8}×\frac {1}{8}=$
$\frac {8}{9}-\frac {1}{6}=$
$\frac {11}{26}×13=$
$10×\frac {9}{20}=$
$4×\frac {3}{8}=$
$\frac {5}{6}×\frac {9}{20}=$
$\frac {4}{5}-\frac {3}{10}=$
$\frac {2}{3}×\frac {3}{4}=$
$\frac {8}{13}×\frac {13}{20}=$
$\frac {5}{9}+\frac {7}{30}=$
$\frac {5}{6}×\frac {8}{15}=$
$\frac {4}{7}×\frac {7}{8}=$

6 $\frac{4}{3}$ 63 $\frac{17}{12}$ $\frac{1}{8}$ $\frac{1}{2}$ 35 $\frac{1}{8}$ $\frac{21}{10}$ $\frac{1}{64}$ $\frac{13}{18}$ $\frac{11}{2}$ $\frac{9}{2}$ $\frac{3}{2}$ $\frac{3}{8}$ $\frac{1}{2}$ $\frac{1}{2}$ $\frac{2}{5}$ $\frac{71}{90}$ $\frac{4}{9}$ $\frac{1}{2}$

$\frac{3}{5}×10=6$
$\frac{8}{9}×1.5=\frac{4}{3}$
$81×\frac{7}{9}=63$
$\frac{2}{3}+\frac{3}{4}=\frac{17}{12}$
$\frac{7}{8}-\frac{3}{4}=\frac{1}{8}$
$\frac{5}{7}×\frac{7}{10}=\frac{1}{2}$
$42×\frac{5}{6}=35$
$\frac{7}{32}×\frac{4}{7}=\frac{1}{8}$
$\frac{5}{2}-\frac{2}{5}=\frac{21}{10}$
$\frac{1}{8}×\frac{1}{8}=\frac{1}{64}$
$\frac{8}{9}-\frac{1}{6}=\frac{13}{18}$
$\frac{11}{26}×13=\frac{11}{2}$
$10×\frac{9}{20}=\frac{9}{2}$
$4×\frac{3}{8}=\frac{3}{2}$
$\frac{5}{6}×\frac{9}{20}=\frac{3}{8}$
$\frac{4}{5}-\frac{3}{10}=\frac{1}{2}$
$\frac{2}{3}×\frac{3}{4}=\frac{1}{2}$
$\frac{8}{13}×\frac{13}{20}=\frac{2}{5}$
$\frac{5}{9}+\frac{7}{30}=\frac{71}{90}$
$\frac{5}{6}×\frac{8}{15}=\frac{4}{9}$
$\frac{4}{7}×\frac{7}{8}=\frac{1}{2}$

二、计算下面各题。
$12×\frac {4}{3}×\frac {4}{7}$
$\frac {6}{5}×\frac {1}{12}×\frac {5}{7}$
$\frac {10}{21}×\frac {12}{25}×\frac {7}{8}$
$\frac {8}{15}×35×\frac {3}{14}$
$\frac {11}{9}×\frac {2}{3}×\frac {21}{22}$
$\frac {9}{32}×\frac {22}{15}×\frac {16}{99}$

$\frac{64}{7}$ $\frac{1}{14}$ $\frac{1}{5}$ 4 $\frac{7}{9}$ $\frac{1}{15}$

1. $12×\frac{4}{3}×\frac{4}{7}$
$\begin{aligned}&12×\frac{4}{3}×\frac{4}{7}\\=&16×\frac{4}{7}\\=&\frac{64}{7}\end{aligned}$
2. $\frac{6}{5}×\frac{1}{12}×\frac{5}{7}$
$\begin{aligned}&\frac{6}{5}×\frac{1}{12}×\frac{5}{7}\\=&\frac{6×1×5}{5×12×7}\\=&\frac{30}{420}\\=&\frac{1}{14}\end{aligned}$
3. $\frac{10}{21}×\frac{12}{25}×\frac{7}{8}$
$\begin{aligned}&\frac{10}{21}×\frac{12}{25}×\frac{7}{8}\\=&\frac{10×12×7}{21×25×8}\\=&\frac{840}{4200}\\=&\frac{1}{5}\end{aligned}$
4. $\frac{8}{15}×35×\frac{3}{14}$
$\begin{aligned}&\frac{8}{15}×35×\frac{3}{14}\\=&\frac{8×35×3}{15×14}\\=&\frac{840}{210}\\=&4\end{aligned}$
5. $\frac{11}{9}×\frac{2}{3}×\frac{21}{22}$
$\begin{aligned}&\frac{11}{9}×\frac{2}{3}×\frac{21}{22}\\=&\frac{11×2×21}{9×3×22}\\=&\frac{462}{594}\\=&\frac{7}{9}\end{aligned}$
6. $\frac{9}{32}×\frac{22}{15}×\frac{16}{99}$
$\begin{aligned}&\frac{9}{32}×\frac{22}{15}×\frac{16}{99}\\=&\frac{9×22×16}{32×15×99}\\=&\frac{3168}{47520}\\=&\frac{1}{15}\end{aligned}$