Question

18．直接寫(xiě)出結(jié)果

$\frac{1}{5}-\frac{1}{7}$=	1÷0.25=	0.5×0.16=	2$\frac{5}{9}$-$1\frac{5}{9}$=1
$（\frac{1}{2}+\frac{1}{4}）×8$=	3+4÷7=	$\frac{3}{8}$÷3=	$6÷（\frac{1}{2}-\frac{1}{3}）$=
$\frac{1}{2}×4-2$=	1+2%=

Answer 1

分析 根據(jù)分?jǐn)?shù)和小數(shù)加減乘除法的計(jì)算方法進(jìn)行計(jì)算．
$（\frac{1}{2}+\frac{1}{4}）×8$根據(jù)乘法分配律進(jìn)行簡(jiǎn)算．

解答 解：

$\frac{1}{5}-\frac{1}{7}$=$\frac{2}{35}$	1÷0.25=4	0.5×0.16=0.08	2$\frac{5}{9}$-$1\frac{5}{9}$=1
$（\frac{1}{2}+\frac{1}{4}）×8$=6	3+4÷7=3$\frac{4}{7}$	$\frac{3}{8}$÷3=$\frac{1}{8}$	$6÷（\frac{1}{2}-\frac{1}{3}）$=36
$\frac{1}{2}×4-2$=0	1+2%=1.02

點(diǎn)評(píng) 口算時(shí)，注意運(yùn)算符號(hào)和數(shù)據(jù)，然后再進(jìn)一步計(jì)算．