1. $\frac {9}{10}+\frac {3}{5}= \frac {3}{5}+$
$\frac{9}{10}$
答案:
$\frac{9}{10}$
2. $(\frac {1}{12}+\frac {3}{4})+(\frac {7}{12}+\frac {1}{4})= (\frac {1}{12}+$
$\frac{7}{12}$
$)+(\frac {3}{4}+$$\frac{1}{4}$
$)$
答案:
$\frac{7}{12}$ $\frac{1}{4}$
3. 在$◯$里填上适当的运算符号。
$\frac {3}{4}◯$
$\frac {19}{20}-(\frac {3}{4}-\frac {1}{5})= \frac {19}{20}◯$
$\frac {3}{4}◯$
$+$
$\frac {1}{6}= \frac {1}{6}+\frac {3}{4}$ $\frac {7}{8}+\frac {2}{5}+\frac {3}{5}= \frac {7}{8}+(\frac {2}{5}◯$$+$
$\frac {3}{5})$ $\frac {19}{20}-(\frac {3}{4}-\frac {1}{5})= \frac {19}{20}◯$
$-$
$\frac {3}{4}◯$$+$
$\frac {1}{5}$
答案:
$+$ $+$ $-$ $+$
4. 在〇里填上“>”“<”或“=”。
$\frac {1}{2}+\frac {1}{3}+\frac {1}{4}$〇
$\frac {1}{4}+\frac {5}{12}+\frac {1}{6}$〇
$\frac {1}{2}+\frac {1}{3}+\frac {1}{4}$〇
>
1 $\frac {3}{5}+\frac {1}{10}-\frac {2}{5}$〇<
$\frac {2}{5}$ $\frac {1}{4}+\frac {5}{12}+\frac {1}{6}$〇
=
$\frac {5}{6}$ $\frac {2}{3}-\frac {1}{8}+\frac {1}{4}$〇>
$\frac {1}{3}$
答案:
$>$ $<$ $=$ $>$
二、计算下列各题,能简算的用简便方法算。
$\frac {1}{3}+\frac {4}{15}+\frac {2}{3}$ $\frac {5}{12}+\frac {1}{3}-\frac {1}{8}$ $\frac {8}{9}+\frac {1}{3}+\frac {3}{8}+\frac {10}{9}$
$\frac {5}{3}-\frac {1}{4}-\frac {3}{4}$ $\frac {2}{3}-(\frac {7}{12}-\frac {1}{3})$ $\frac {9}{17}+(\frac {5}{12}+\frac {8}{17})$
$\frac {1}{3}+\frac {4}{15}+\frac {2}{3}$ $\frac {5}{12}+\frac {1}{3}-\frac {1}{8}$ $\frac {8}{9}+\frac {1}{3}+\frac {3}{8}+\frac {10}{9}$
$\frac {5}{3}-\frac {1}{4}-\frac {3}{4}$ $\frac {2}{3}-(\frac {7}{12}-\frac {1}{3})$ $\frac {9}{17}+(\frac {5}{12}+\frac {8}{17})$
答案:
1 $\frac{4}{15}$ $\frac{5}{8}$ 2 $\frac{17}{24}$ $\frac{2}{3}$ $\frac{5}{12}$ 1 $\frac{5}{12}$
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