《2025年口算基础训练六年级数学上册人教版》

合理计算
(1)$640× \frac{7}{8}× \frac{3}{4}$
(7)$(\frac{8}{9}+\frac{5}{6})× 5.4$
(2)$180× \frac{2}{3}× \frac{5}{12}$
(8)$\frac{7}{13}× \frac{5}{11}+\frac{5}{13}× \frac{4}{11}$
(3)$38× (\frac{5}{19}× 1.2)$
(9)$(\frac{7}{8}+\frac{1}{6}-\frac{3}{4})× 2.4$
(4)$\frac{11}{16}× 32× \frac{9}{11}$
(10)$\frac{3}{4}× \frac{5}{8}+\frac{1}{4}× \frac{5}{8}+\frac{5}{8}$
(5)$2.5× \frac{3}{5}+2.5$
(11)$(\frac{2}{17}× \frac{2}{19})× 17× 19$
(6)$3.2-3.2× \frac{1}{8}$
(12)$(\frac{2}{17}+\frac{2}{19})× 17× 19$

答案：
(1) $640×\frac{7}{8}×\frac{3}{4}$
$=80×7×\frac{3}{4}$
$=560×\frac{3}{4}$
$=140×3$
$=420$
(2) $180×\frac{2}{3}×\frac{5}{12}$
$=60×2×\frac{5}{12}$
$=120×\frac{5}{12}$
$=10×5$
$=50$
(3) $38×(\frac{5}{19}×1.2)$
$=38×\frac{5}{19}×1.2$
$=2×5×1.2$
$=10×1.2$
$=12$
(4) $\frac{11}{16}×32×\frac{9}{11}$
$=\frac{11}{16}×\frac{9}{11}×32$
$=\frac{9}{16}×32$
$=9×2$
$=18$
(5) $2.5×\frac{3}{5}+2.5$
$=2.5×\frac{3}{5}+2.5×1$
$=2.5×(\frac{3}{5}+1)$
$=2.5×\frac{8}{5}$
$=0.5×8$
$=4$
(6) $3.2 - 3.2×\frac{1}{8}$
$=3.2×(1 - \frac{1}{8})$
$=3.2×\frac{7}{8}$
$=0.4×7$
$=2.8$
(7) $(\frac{8}{9}+\frac{5}{6})×5.4$
$=\frac{8}{9}×5.4 + \frac{5}{6}×5.4$
$=8×0.6 + 5×0.9$
$=4.8 + 4.5$
$=9.3$
(8) $\frac{7}{13}×\frac{5}{11}+\frac{5}{13}×\frac{4}{11}$
$=\frac{5}{13}×\frac{7}{11}+\frac{5}{13}×\frac{4}{11}$
$=\frac{5}{13}×(\frac{7}{11}+\frac{4}{11})$
$=\frac{5}{13}×1$
$=\frac{5}{13}$
(9) $(\frac{7}{8}+\frac{1}{6}-\frac{3}{4})×2.4$
$=\frac{7}{8}×2.4 + \frac{1}{6}×2.4 - \frac{3}{4}×2.4$
$=7×0.3 + 1×0.4 - 3×0.6$
$=2.1 + 0.4 - 1.8$
$=2.5 - 1.8$
$=0.7$
(10) $\frac{3}{4}×\frac{5}{8}+\frac{1}{4}×\frac{5}{8}+\frac{5}{8}$
$=(\frac{3}{4}+\frac{1}{4}+1)×\frac{5}{8}$
$=(1 + 1)×\frac{5}{8}$
$=2×\frac{5}{8}$
$=\frac{5}{4}$
(11) $(\frac{2}{17}×\frac{2}{19})×17×19$
$=\frac{2}{17}×17×\frac{2}{19}×19$
$=2×2$
$=4$
(12) $(\frac{2}{17}+\frac{2}{19})×17×19$
$=\frac{2}{17}×17×19 + \frac{2}{19}×17×19$
$=2×19 + 2×17$
$=38 + 34$
$=72$