题目内容
3.计算下列各题.1+0.45÷0.9-$\frac{7}{8}$
($\frac{1}{3}$-$\frac{1}{5}$)×45
$\frac{4}{7}×[{0.75-({\frac{7}{16}-0.25})}]$.
分析 (1)先算除法,再算加法,最后算减法.
(2)根据乘法的分配律简算即可.
(3)根据减法的性质、加法的交换律简算即可.
解答 解:(1)1+0.45÷0.9-$\frac{7}{8}$
=1+0.5-$\frac{7}{8}$
=1.5-$\frac{7}{8}$
=0.625
(2)($\frac{1}{3}$-$\frac{1}{5}$)×45
=$\frac{1}{3}$×45-$\frac{1}{5}$×45
=15-9
=6
(3)$\frac{4}{7}×[{0.75-({\frac{7}{16}-0.25})}]$
=$\frac{4}{7}$×[0.75-$\frac{7}{16}$+0.25]
=$\frac{4}{7}$×[0.75+0.25-$\frac{7}{16}$]
=$\frac{4}{7}$×[1-$\frac{7}{16}$]
=$\frac{4}{7}$×$\frac{9}{16}$
=$\frac{9}{28}$
点评 计算四则混合运算时,要注意按照运算顺序计算;不要错用运算定律.
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1÷0.25= | $\frac{5}{8}$÷0.125= | 1.2x+2.1x= | 102= |
125×8= | 3.6×$\frac{5}{9}$= | 3.3-1.27= | 5+5÷$\frac{1}{5}$= |