一、口算。
$36×\frac {3}{4}=$
$\frac {3}{11}×3=$
$\frac {11}{15}×5=$
$8×\frac {5}{18}=$
$\frac {9}{20}×15=$
$\frac {5}{7}×49=$
$15×\frac {1}{5}=$
$\frac {3}{8}×24=$
$\frac {5}{8}×12=$
$\frac {3}{8}×8=$
$\frac {5}{8}×16=$
$\frac {5}{6}×3=$
$12×0.75=$
$7×\frac {3}{14}=$
$\frac {5}{28}×7=$
$\frac {4}{9}×18=$
$\frac {4}{7}×28=$
$\frac {5}{6}×24=$
$33×\frac {2}{11}=$
$14×\frac {4}{7}=$
$\frac {5}{6}×18=$

27 $\frac{9}{11}$ $\frac{11}{3}$ $\frac{20}{9}$ $\frac{27}{4}$ 35 3 9 $\frac{15}{2}$ 3 10 $\frac{5}{2}$ 9 $\frac{3}{2}$ $\frac{5}{4}$ 8 16 20 6 8 15

$36×\frac {3}{4}=27$
$\frac {3}{11}×3=\frac {9}{11}$
$\frac {11}{15}×5=\frac {11}{3}$
$8×\frac {5}{18}=\frac {20}{9}$
$\frac {9}{20}×15=\frac {27}{4}$
$\frac {5}{7}×49=35$
$15×\frac {1}{5}=3$
$\frac {3}{8}×24=9$
$\frac {5}{8}×12=\frac {15}{2}$
$\frac {3}{8}×8=3$
$\frac {5}{8}×16=10$
$\frac {5}{6}×3=\frac {5}{2}$
$12×0.75=9$
$7×\frac {3}{14}=\frac {3}{2}$
$\frac {5}{28}×7=\frac {5}{4}$
$\frac {4}{9}×18=8$
$\frac {4}{7}×28=16$
$\frac {5}{6}×24=20$
$33×\frac {2}{11}=6$
$14×\frac {4}{7}=8$
$\frac {5}{6}×18=15$

1. $\frac {2}{5}+\frac {2}{5}+\frac {2}{5}+\frac {2}{5}+\frac {2}{5}= \frac {2}{5}×()= ()$

1. 5 2

$\frac{2}{5}+\frac{2}{5}+\frac{2}{5}+\frac{2}{5}+\frac{2}{5}=\frac{2}{5}×5=2$

2. $\frac {5}{9}×4= ($$)+($$)+($$)+($$)$

2. $\frac{5}{9}$ $\frac{5}{9}$ $\frac{5}{9}$ $\frac{5}{9}$

3. $\underbrace {\frac {3}{5}+\frac {3}{5}+... +\frac {3}{5}}_{100个\frac {3}{5}}= ()×()= ()$

3. $\frac{3}{5}$ 100 60

$\underbrace {\frac {3}{5}+\frac {3}{5}+... +\frac {3}{5}}_{100个\frac {3}{5}}=(\frac{3}{5})×(100)=(60)$

4. $\frac {1}{5}$的3倍是(),6个$\frac {1}{3}$是()。

4. $\frac{3}{5}$ 2