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一、填一填。
1. $\frac{8}{9} × 16 × \frac{9}{8} = (\quad) × (\quad) × 16$，运用了(
1. $\frac{8}{9} × 16 × \frac{9}{8} = (\quad) × (\quad) × 16$，运用了(
乘法交换
)律。答案
1. $\frac{8}{9}$ $\frac{9}{8}$ 乘法交换
2. $64×\frac{6}{7}×\frac{7}{6}=64×(\_\_\_\_\_\_×\_\_\_\_\_\_)$,运用了(
乘法结合
)律。答案
2. $\frac{6}{7}$ $\frac{7}{6}$ 乘法结合
3. $(\dfrac{2}{7}+\dfrac{5}{7})×\dfrac{3}{5}=(\quad)×\dfrac{3}{5}+(\quad)×\dfrac{3}{5}$，运用了(
乘法分配
)律。答案
3. $\frac{2}{7}$ $\frac{5}{7}$ 乘法分配
二、计算下面各题。
$\frac{3}{13} × \frac{26}{29} + \frac{5}{29}$
$\frac{5}{14} + \frac{9}{14} × \frac{1}{3}$
$\frac{11}{16} × 4 × \frac{2}{11} × 8$
$\frac{7}{9} + \frac{2}{9} × \frac{3}{5}$
$\frac{7}{8} × 24 × \frac{5}{21}$
$\frac{8}{9} × [ \frac{3}{5} × ( \frac{7}{16} - \frac{1}{4} ) ]$
$\frac{3}{13} × \frac{26}{29} + \frac{5}{29}$
$\frac{5}{14} + \frac{9}{14} × \frac{1}{3}$
$\frac{11}{16} × 4 × \frac{2}{11} × 8$
$\frac{7}{9} + \frac{2}{9} × \frac{3}{5}$
$\frac{7}{8} × 24 × \frac{5}{21}$
$\frac{8}{9} × [ \frac{3}{5} × ( \frac{7}{16} - \frac{1}{4} ) ]$
答案
1. $\frac{11}{29}$ 2. $\frac{4}{7}$ 3. 4 4. $\frac{41}{45}$ 5. 5 6. $\frac{1}{10}$
三、用运算律进行简便计算。
$\frac{3}{4}×\frac{5}{14}×\frac{7}{15}$
$(\frac{1}{2}-\frac{1}{3}+\frac{1}{9})×18$
$3×\frac{3}{13}+3×\frac{10}{13}$
$25×\frac{3}{8}$
$\frac{11}{9}×\frac{5}{7}-\frac{2}{9}×\frac{5}{7}$
$\frac{1}{4}×\frac{5}{8}+0.75×\frac{5}{8}$
$\frac{3}{4}×\frac{5}{14}×\frac{7}{15}$
$(\frac{1}{2}-\frac{1}{3}+\frac{1}{9})×18$
$3×\frac{3}{13}+3×\frac{10}{13}$
$25×\frac{3}{8}$
$\frac{11}{9}×\frac{5}{7}-\frac{2}{9}×\frac{5}{7}$
$\frac{1}{4}×\frac{5}{8}+0.75×\frac{5}{8}$
答案
1. $\frac{1}{8}$ 2. 5 3. 3 4. $\frac{75}{8}$ 5. $\frac{5}{7}$ 6. $\frac{5}{8}$
