1. 直接写得数。
$\frac{4}{5}+\frac{1}{5}=$
$\frac{1}{12}+\frac{1}{4}=$
$\frac{1}{2}-\frac{3}{10}=$
$\frac{4}{5}+\frac{1}{5}=$
1
$\frac{1}{2}-\frac{1}{4}=$$\frac{1}{4}$
$\frac{8}{21}+\frac{1}{21}=$$\frac{3}{7}$
$8-\frac{6}{5}=$$6\frac{4}{5}$
$\frac{1}{12}+\frac{1}{4}=$
$\frac{1}{3}$
$1-\frac{5}{8}=$$\frac{3}{8}$
$\frac{3}{4}-\frac{1}{4}=$$\frac{1}{2}$
$\frac{5}{8}+\frac{7}{8}=$$\frac{3}{2}$
$\frac{1}{2}-\frac{3}{10}=$
$\frac{1}{5}$
$\frac{1}{2}+\frac{1}{3}=$$\frac{5}{6}$
$\frac{4}{5}+\frac{1}{10}=$$\frac{9}{10}$
$\frac{9}{20}-\frac{1}{4}=$$\frac{1}{5}$
答案:
1 $\frac{1}{4}$ $\frac{3}{7}$ 6 $\frac{4}{5}$ $\frac{1}{3}$ $\frac{3}{8}$ $\frac{1}{2}$ $\frac{3}{2}$ $\frac{1}{5}$ $\frac{5}{6}$ $\frac{9}{10}$ $\frac{1}{5}$
2. 用简便方法计算。
$\frac{2}{5}+\frac{1}{3}+\frac{3}{5}$ $9-\frac{4}{13}-\frac{9}{13}$ $\frac{5}{6}-\frac{1}{3}-\frac{1}{2}$
$\frac{9}{7}+\frac{3}{8}+\frac{1}{8}+\frac{5}{7}$ $\frac{7}{12}-(\frac{4}{9}-\frac{5}{12})$ $\frac{3}{8}+\frac{5}{7}+\frac{5}{8}+\frac{2}{7}$
$\frac{2}{5}+\frac{1}{3}+\frac{3}{5}$ $9-\frac{4}{13}-\frac{9}{13}$ $\frac{5}{6}-\frac{1}{3}-\frac{1}{2}$
$\frac{9}{7}+\frac{3}{8}+\frac{1}{8}+\frac{5}{7}$ $\frac{7}{12}-(\frac{4}{9}-\frac{5}{12})$ $\frac{3}{8}+\frac{5}{7}+\frac{5}{8}+\frac{2}{7}$
答案:
$1\frac{1}{3}$ 8 0 $2\frac{1}{2}$ $\frac{5}{9}$ 2
妈妈买来一些毛线,给爸爸织毛衣用去$\frac{7}{15}$,给儿子织手套用去$\frac{1}{30}$,给女儿织围巾用去$\frac{3}{20}$。
(1)织毛衣和织手套共用了毛线的几分之几?
(2)织毛衣比织围巾多用去毛线的几分之几?
(1)织毛衣和织手套共用了毛线的几分之几?
(2)织毛衣比织围巾多用去毛线的几分之几?
答案:
(1) $\frac{1}{2}$
(2) $\frac{19}{60}$
(1) $\frac{1}{2}$
(2) $\frac{19}{60}$
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