Question

19．直接寫(xiě)出得數(shù)

$\frac{5}{9}$×15=	$\frac{3}{5}$×2=	$\frac{1}{4}$×$\frac{4}{5}$=	$\frac{1}{9}$×$\frac{3}{7}$=	$\frac{7}{12}$×$\frac{3}{4}$=
$\frac{2}{3}$÷$\frac{1}{9}$=	0÷$\frac{5}{8}$=	$\frac{9}{53}$÷$\frac{9}{53}$=	$\frac{1}{10}$×$\frac{5}{8}$=	$\frac{1}{3}$+$\frac{1}{17}$=

Answer 1

分析 根據(jù)分?jǐn)?shù)的加法及乘除法的計(jì)算法則進(jìn)行口算，注意計(jì)算結(jié)果化成最簡(jiǎn)分?jǐn)?shù)．

解答

解：$\frac{5}{9}$×15=$\frac{25}{3}$	$\frac{3}{5}$×2=$\frac{6}{5}$	$\frac{1}{4}$×$\frac{4}{5}$=$\frac{1}{5}$	$\frac{1}{9}$×$\frac{3}{7}$=$\frac{1}{21}$	$\frac{7}{12}$×$\frac{3}{4}$=$\frac{7}{16}$
$\frac{2}{3}$÷$\frac{1}{9}$=6	0÷$\frac{5}{8}$=0	$\frac{9}{53}$÷$\frac{9}{53}$=1	$\frac{1}{10}$×$\frac{5}{8}$=$\frac{1}{16}$	$\frac{1}{3}$+$\frac{1}{17}$=$\frac{20}{51}$

點(diǎn)評(píng) 注意分?jǐn)?shù)表示計(jì)算結(jié)果，一定要化成最簡(jiǎn)分?jǐn)?shù)，注意運(yùn)算的順序．