《2025年心算口算巧算六年级上册北师大版》

计算下面各题。$1.1 × 50\% =$

答案： 0.55

2 脱式计算。(能简算的要简算)
$(\frac{2}{5}-\frac{2}{5}÷2)×\frac{5}{3}$
$\frac{7}{16}-(\frac{7}{12}+\frac{1}{6})×\frac{1}{2}$
$\frac{8}{25}×99+\frac{8}{25}$
$(1-75\%)÷(1+\frac{1}{4})$
$204÷\frac{1}{91}+204×9$
$2.7÷(1-10\%-18\%)$
$(1-\frac{1}{4})×\frac{5}{6}÷2$
$(\frac{1}{2}+\frac{1}{4})×12-\frac{1}{2}$
$(\frac{3}{4}+\frac{1}{4})÷\frac{2}{5}×\frac{3}{5}$

答案： $\frac{1}{3}$；$\frac{1}{48}$；32；$\frac{1}{5}$；20400；3.75；$\frac{5}{16}$；8$\frac{1}{2}$；$\frac{3}{2}$
$(\frac{2}{5}-\frac{2}{5}÷2)×\frac{5}{3}$
$=(\frac{2}{5}-\frac{1}{5})×\frac{5}{3}$
$=\frac{1}{5}×\frac{5}{3}$
$=\frac{1}{3}$
$\frac{7}{16}-(\frac{7}{12}+\frac{1}{6})×\frac{1}{2}$
$=\frac{7}{16}-(\frac{7}{12}+\frac{2}{12})×\frac{1}{2}$
$=\frac{7}{16}-\frac{9}{12}×\frac{1}{2}$
$=\frac{7}{16}-\frac{3}{8}$
$=\frac{7}{16}-\frac{6}{16}$
$=\frac{1}{16}×\frac{1}{3}$（此处原解析有误，重新计算：$\frac{9}{12}×\frac{1}{2}=\frac{3}{4}×\frac{1}{2}=\frac{3}{8}=\frac{6}{16}$，$\frac{7}{16}-\frac{6}{16}=\frac{1}{16}$，正确结果应为$\frac{1}{16}$，但原答案可能有误，按正确步骤应为$\frac{1}{16}$）
$\frac{8}{25}×99+\frac{8}{25}$
$=\frac{8}{25}×(99+1)$
$=\frac{8}{25}×100$
$=32$
$(1-75\%)÷(1+\frac{1}{4})$
$=0.25÷\frac{5}{4}$
$=\frac{1}{4}×\frac{4}{5}$
$=\frac{1}{5}$
$204÷\frac{1}{91}+204×9$
$=204×91+204×9$
$=204×(91+9)$
$=204×100$
$=20400$
$2.7÷(1-10\%-18\%)$
$=2.7÷0.72$
$=3.75$
$(1-\frac{1}{4})×\frac{5}{6}÷2$
$=\frac{3}{4}×\frac{5}{6}×\frac{1}{2}$
$=\frac{15}{24}×\frac{1}{2}$
$=\frac{5}{8}×\frac{1}{2}$
$=\frac{5}{16}$
$(\frac{1}{2}+\frac{1}{4})×12-\frac{1}{2}$
$=(\frac{2}{4}+\frac{1}{4})×12-\frac{1}{2}$
$=\frac{3}{4}×12-\frac{1}{2}$
$=9-\frac{1}{2}$
$=8\frac{1}{2}$
$(\frac{3}{4}+\frac{1}{4})÷\frac{2}{5}×\frac{3}{5}$
$=1×\frac{5}{2}×\frac{3}{5}$
$=\frac{3}{2}$