Question

13．計(jì)算．

$\frac{9}{10}$÷$\frac{3}{8}$÷$\frac{2}{5}$	40÷$\frac{8}{9}$	3×$\frac{4}{9}$÷$\frac{3}{8}$	$\frac{8}{45}$÷$\frac{1}{20}$
$\frac{1}{2}$÷$\frac{4}{7}$×$\frac{7}{4}$	$\frac{16}{9}$÷$\frac{8}{11}$÷$\frac{22}{3}$	$\frac{7}{9}$×$\frac{3}{14}$÷$\frac{5}{6}$	$\frac{8}{9}$÷$\frac{5}{18}$÷10．

Answer 1

分析 ①②④把除法轉(zhuǎn)化成乘法，直接約分計(jì)算即可；
③⑦先算乘法，再算除法即可；
⑤先算除法，再算乘法即可；
⑥把除法轉(zhuǎn)化成乘法，利用乘法交換律結(jié)合律，約分計(jì)算即可；
⑧由左向右的順序計(jì)算即可．

解答 解：①$\frac{9}{10}$÷$\frac{3}{8}$÷$\frac{2}{5}$
=$\frac{9}{10}$×$\frac{8}{3}$÷$\frac{2}{5}$
=$\frac{12}{5}$×$\frac{5}{2}$
=6

②40÷$\frac{8}{9}$
=40×$\frac{9}{8}$
=45

③3×$\frac{4}{9}$÷$\frac{3}{8}$
=$\frac{4}{3}$÷$\frac{3}{8}$
=$\frac{32}{9}$

④$\frac{8}{45}$÷$\frac{1}{20}$
=$\frac{8}{45}$×20
=$\frac{32}{9}$

⑤$\frac{1}{2}$÷$\frac{4}{7}$×$\frac{7}{4}$
=$\frac{7}{8}$×$\frac{7}{4}$
=$\frac{49}{32}$

⑥$\frac{16}{9}$÷$\frac{8}{11}$÷$\frac{22}{3}$
=（$\frac{16}{9}$×$\frac{3}{22}$）×$\frac{11}{8}$
=$\frac{8}{33}$×$\frac{11}{8}$
=$\frac{1}{3}$

⑦$\frac{7}{9}$×$\frac{3}{14}$÷$\frac{5}{6}$
=$\frac{1}{6}÷\frac{5}{6}$
=$\frac{1}{5}$

⑧$\frac{8}{9}$÷$\frac{5}{18}$÷10
=$\frac{16}{5}$÷10
=$\frac{8}{25}$

點(diǎn)評(píng) 此題考查了分?jǐn)?shù)四則混合運(yùn)算的順序，注意約分，認(rèn)真計(jì)算即可．