《2025年心算口算巧算六年级上册北师大版》

计算下面各题。
$25 + 25×\frac{1}{5}$
$\frac{1}{4}×\frac{3}{5}×\frac{4}{3}$
$\frac{2}{5}×(\frac{1}{2} - \frac{1}{4})$
$30×(\frac{2}{5} - \frac{1}{10})$
$12×(\frac{1}{6} + \frac{2}{3})$
$\frac{2}{3}×\frac{3}{8}×\frac{2}{7}$
$\frac{3}{5}×6×15$
$\frac{2}{5}×\frac{1}{12}×\frac{3}{4}$
$\frac{3}{14}×(\frac{1}{5} + \frac{4}{5})$
$\frac{3}{7}×(\frac{8}{9} - \frac{5}{9})$
$\frac{1}{22}×18 + \frac{21}{22}×18$
$\frac{4}{5}×\frac{6}{5}×\frac{2}{9}$

答案： $25 + 25×\frac{1}{5}$
解：$25 + 5 = 30$
$\frac{1}{4}×\frac{3}{5}×\frac{4}{3}$
解：$\frac{1}{4}×(\frac{3}{5}×\frac{4}{3})=\frac{1}{4}×\frac{4}{5}=\frac{1}{5}$
$\frac{2}{5}×(\frac{1}{2} - \frac{1}{4})$
解：$\frac{1}{2} - \frac{1}{4}=\frac{1}{4}$，$\frac{2}{5}×\frac{1}{4}=\frac{1}{10}$
$30×(\frac{2}{5} - \frac{1}{10})$
解：$\frac{2}{5} - \frac{1}{10}=\frac{3}{10}$，$30×\frac{3}{10}=9$
$12×(\frac{1}{6} + \frac{2}{3})$
解：$\frac{1}{6} + \frac{2}{3}=\frac{5}{6}$，$12×\frac{5}{6}=10$
$\frac{2}{3}×\frac{3}{8}×\frac{2}{7}$
解：$\frac{6}{24}=\frac{1}{4}$，$\frac{1}{4}×\frac{2}{7}=\frac{1}{14}$
$\frac{3}{5}×6×15$
解：$\frac{3}{5}×15=9$，$9×6=54$
$\frac{2}{5}×\frac{1}{12}×\frac{3}{4}$
解：$\frac{2}{60}=\frac{1}{30}$，$\frac{1}{30}×\frac{3}{4}=\frac{1}{40}$
$\frac{3}{14}×(\frac{1}{5} + \frac{4}{5})$
解：$\frac{1}{5} + \frac{4}{5}=1$，$\frac{3}{14}×1=\frac{3}{14}$
$\frac{3}{7}×(\frac{8}{9} - \frac{5}{9})$
解：$\frac{8}{9} - \frac{5}{9}=\frac{1}{3}$，$\frac{3}{7}×\frac{1}{3}=\frac{1}{7}$
$\frac{1}{22}×18 + \frac{21}{22}×18$
解：$18×(\frac{1}{22} + \frac{21}{22})=18×1=18$
$\frac{4}{5}×\frac{6}{5}×\frac{2}{9}$
解：$\frac{24}{25}×\frac{2}{9}=\frac{16}{75}$