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1. 看图写出算式。
(1)
$\frac{1}{4}+\frac{1}{4}+\frac{1}{4}= \frac{3}{4}$
$\frac{1}{4}×3= \frac{3}{4}$
(2)
$\frac{2}{9}+\frac{2}{9}+\frac{2}{9}+\frac{2}{9}= \frac{8}{9}$
$\frac{2}{9}×4= \frac{8}{9}$
(1)
$\frac{1}{4}+\frac{1}{4}+\frac{1}{4}= \frac{3}{4}$
$\frac{1}{4}×3= \frac{3}{4}$
(2)
$\frac{2}{9}+\frac{2}{9}+\frac{2}{9}+\frac{2}{9}= \frac{8}{9}$
$\frac{2}{9}×4= \frac{8}{9}$
答案
1.
(1)$\frac{1}{4}+\frac{1}{4}+\frac{1}{4}=\frac{3}{4}$ $\frac{1}{4}× 3=\frac{3}{4}$
(2)$\frac{2}{9}+\frac{2}{9}+\frac{2}{9}+\frac{2}{9}=\frac{8}{9}$ $\frac{2}{9}× 4=\frac{8}{9}$
(1)$\frac{1}{4}+\frac{1}{4}+\frac{1}{4}=\frac{3}{4}$ $\frac{1}{4}× 3=\frac{3}{4}$
(2)$\frac{2}{9}+\frac{2}{9}+\frac{2}{9}+\frac{2}{9}=\frac{8}{9}$ $\frac{2}{9}× 4=\frac{8}{9}$
2. 先分一分,后涂一涂,再用乘法计算。
(1)12的$\frac{1}{4}$是多少？
(2)20的$\frac{4}{5}$是多少？
(1)12的$\frac{1}{4}$是多少？
(2)20的$\frac{4}{5}$是多少？
答案
2.
(1)$12× \frac{1}{4}=3$
(2)$20× \frac{4}{5}=16$
(1)$12× \frac{1}{4}=3$
(2)$20× \frac{4}{5}=16$
3. 计算下面各题。
$\frac{2}{5}×2$
$\frac{5}{8}×4$
$39×\frac{2}{13}$
$17×\frac{7}{51}$
$58×\frac{5}{87}$
$\frac{2}{5}×2$
$\frac{5}{8}×4$
$39×\frac{2}{13}$
$17×\frac{7}{51}$
$58×\frac{5}{87}$
答案
3.$\frac{4}{5}$ $\frac{5}{2}$ 6 $\frac{7}{3}$ $\frac{10}{3}$
解析
$\frac{2}{5}×2 = \frac{4}{5}$
$\frac{5}{8}×4 = \frac{5×4}{8} = \frac{5}{2}$
$39×\frac{2}{13} = 3×2 = 6$
$17×\frac{7}{51} = \frac{7}{3}$
$58×\frac{5}{87} = \frac{58×5}{87} = \frac{10}{3}$
$\frac{5}{8}×4 = \frac{5×4}{8} = \frac{5}{2}$
$39×\frac{2}{13} = 3×2 = 6$
$17×\frac{7}{51} = \frac{7}{3}$
$58×\frac{5}{87} = \frac{58×5}{87} = \frac{10}{3}$
4. 小华打算用木条做一个边长为$\frac{5}{12}$m的正方形相框,他至少需要准备多少米的木条？
答案
4.$\frac{5}{12}× 4=\frac{5}{3}$(米)
解析
$\frac{5}{12} × 4 = \frac{5}{3}$（米）
5. 小明家住15楼,他从1楼到2楼用了$\frac{9}{16}$分钟,照这样的速度,他从1楼到家要用多少分钟？
答案
5.$\frac{9}{16}× (15-1)=\frac{63}{8}$(分钟)
解析
$\frac{9}{16} × (15 - 1) = \frac{9}{16} × 14 = \frac{63}{8}$(分钟)
