Question

12．口算

$\frac{3}{4}$×$\frac{8}{9}$	7×$\frac{8}{21}$	3.3×$\frac{2}{11}$	$\frac{5}{8}$×1.6	2$\frac{2}{15}$×$\frac{5}{6}$
8÷$\frac{1}{8}$	$\frac{2}{5}$÷10	$\frac{3}{4}$÷1$\frac{1}{5}$	3.6÷$\frac{3}{4}$	$\frac{9}{20}$÷15

Answer 1

分析 根據(jù)分?jǐn)?shù)加法、分?jǐn)?shù)減法、分?jǐn)?shù)乘法、分?jǐn)?shù)除法的計(jì)算法則，依次進(jìn)行計(jì)算即可．

解答 解：

$\frac{3}{4}$×$\frac{8}{9}$=$\frac{2}{3}$	7×$\frac{8}{21}$=$\frac{8}{3}$	3.3×$\frac{2}{11}$=0.6	$\frac{5}{8}$×1.6=1	2$\frac{2}{15}$×$\frac{5}{6}$=$\frac{16}{9}$
8÷$\frac{1}{8}$=64	$\frac{2}{5}$÷10=$\frac{1}{25}$	$\frac{3}{4}$÷1$\frac{1}{5}$=$\frac{5}{8}$	3.6÷$\frac{3}{4}$=4.8	$\frac{9}{20}$÷15=$\frac{3}{100}$

點(diǎn)評 明確分?jǐn)?shù)加法、分?jǐn)?shù)減法、分?jǐn)?shù)乘法、分?jǐn)?shù)除法的計(jì)算法則，是解答此題的關(guān)鍵．