Question

12．口算

$\frac{5}{9}$×15=	$\frac{1}{4}$×$\frac{4}{5}$=	$\frac{1}{9}$×$\frac{3}{7}$=	$\frac{7}{12}$×$\frac{3}{4}$=
2.8×$\frac{7}{24}$×0=	$\frac{6}{11}$×$\frac{1}{12}$=	$\frac{3}{22}$×$\frac{11}{13}$=	$\frac{7}{6}$×2.4=
$\frac{3}{4}$×$\frac{1}{5}$=	$\frac{4}{7}$×$\frac{3}{8}$×1.4=

Answer 1

分析 根據分數乘法的計算方法進行解答即可，$\frac{4}{7}$×$\frac{3}{8}$×1.4直接約分計算．

解答 解：

$\frac{5}{9}$×15=$\frac{25}{3}$	$\frac{1}{4}$×$\frac{4}{5}$=$\frac{1}{5}$	$\frac{1}{9}$×$\frac{3}{7}$=$\frac{1}{21}$	$\frac{7}{12}$×$\frac{3}{4}$=$\frac{7}{16}$
2.8×$\frac{7}{24}$×0=0	$\frac{6}{11}$×$\frac{1}{12}$=$\frac{1}{22}$	$\frac{3}{22}$×$\frac{11}{13}$=$\frac{3}{26}$	$\frac{7}{6}$×2.4=2.8
$\frac{3}{4}$×$\frac{1}{5}$=$\frac{3}{20}$	$\frac{4}{7}$×$\frac{3}{8}$×1.4=0.3

點評 此題考查了分數乘法的口算能力．