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1. $(-16)×(-2)×(-5)= $
答案
-160
解析
$(-16)×(-2)×(-5)$
$=(-16)×[(-2)×(-5)]$
$=(-16)×10$
$=-160$
$=(-16)×[(-2)×(-5)]$
$=(-16)×10$
$=-160$
2. $0.25×(-\frac {1}{6})×4= $
答案
$-\frac{1}{6}$
解析
$0.25×(-\frac{1}{6})×4$
$=0.25×4×(-\frac{1}{6})$
$=1×(-\frac{1}{6})$
$=-\frac{1}{6}$
$=0.25×4×(-\frac{1}{6})$
$=1×(-\frac{1}{6})$
$=-\frac{1}{6}$
3. $(-\frac {2}{3})×( )= 1$
答案
$-\frac{3}{2}$
4. $(-8)×9+18×9= $
答案
90
解析
$(-8) × 9 + 18 × 9$
$=9×(-8 + 18)$
$=9×10$
$=90$
$=9×(-8 + 18)$
$=9×10$
$=90$
5. $(-4.25)×( )= 1$
答案
$-\frac{4}{17}$
解析
设括号内的数为$x$，则$(-4.25)x = 1$，$-4.25=-\frac{17}{4}$，所以$-\frac{17}{4}x = 1$，解得$x=1÷(-\frac{17}{4})=1×(-\frac{4}{17})=-\frac{4}{17}$。$-\frac{4}{17}$
6. $[3×(-25)]×(-2)= $
答案
150
解析
$\begin{aligned}[3×(-25)]×(-2)&=3×[(-25)×(-2)]\\&=3×50\\&=150\end{aligned}$
7. $4×(-7)×(-125)= $
答案
3500
解析
$4×(-7)×(-125)$
$=4×(-125)×(-7)$
$=(-500)×(-7)$
$=3500$
$=4×(-125)×(-7)$
$=(-500)×(-7)$
$=3500$
8. $(-20)×[(+\frac {1}{4})+(-\frac {1}{5})-(-1)]= $
答案
-21
解析
$(-20)×[(+\frac{1}{4})+(-\frac{1}{5})-(-1)]$
$=(-20)×(\frac{1}{4}-\frac{1}{5}+1)$
$=(-20)×\frac{1}{4}+(-20)×(-\frac{1}{5})+(-20)×1$
$=-5 + 4 - 20$
$=-21$
$=(-20)×(\frac{1}{4}-\frac{1}{5}+1)$
$=(-20)×\frac{1}{4}+(-20)×(-\frac{1}{5})+(-20)×1$
$=-5 + 4 - 20$
$=-21$
9. $(-56)×(+\frac {1}{3})×(-9)×(+\frac {1}{8})$
答案
21
解析
$(-56) × (+\frac{1}{3}) × (-9) × (+\frac{1}{8})$
$=(-56) × (+\frac{1}{8}) × (+\frac{1}{3}) × (-9)$
$=(-7) × (-3)$
$=21$
$=(-56) × (+\frac{1}{8}) × (+\frac{1}{3}) × (-9)$
$=(-7) × (-3)$
$=21$
10. $(-18)×[(+\frac {1}{3})-(-\frac {1}{9})]$
答案
-8
解析
$(-18)×\left[(+\frac{1}{3})-(-\frac{1}{9})\right]$
$=(-18)×\left(\frac{1}{3}+\frac{1}{9}\right)$
$=(-18)×\frac{4}{9}$
$=-8$
$=(-18)×\left(\frac{1}{3}+\frac{1}{9}\right)$
$=(-18)×\frac{4}{9}$
$=-8$
11. $\frac {1}{8}-0.125×5+\frac {3}{8}×5-0.625×7$
答案
-3
解析
$\frac{1}{8} - 0.125 × 5 + \frac{3}{8} × 5 - 0.625 × 7$
$=\frac{1}{8} - \frac{1}{8} × 5 + \frac{3}{8} × 5 - \frac{5}{8} × 7$
$=\frac{1}{8} + 5 × (\frac{3}{8} - \frac{1}{8}) - \frac{35}{8}$
$=\frac{1}{8} + 5 × \frac{2}{8} - \frac{35}{8}$
$=\frac{1}{8} + \frac{10}{8} - \frac{35}{8}$
$=\frac{1 + 10 - 35}{8}$
$=\frac{-24}{8}$
$=-3$
$=\frac{1}{8} - \frac{1}{8} × 5 + \frac{3}{8} × 5 - \frac{5}{8} × 7$
$=\frac{1}{8} + 5 × (\frac{3}{8} - \frac{1}{8}) - \frac{35}{8}$
$=\frac{1}{8} + 5 × \frac{2}{8} - \frac{35}{8}$
$=\frac{1}{8} + \frac{10}{8} - \frac{35}{8}$
$=\frac{1 + 10 - 35}{8}$
$=\frac{-24}{8}$
$=-3$
12. $-(-99\frac {15}{16})×8$
答案
$799\frac{1}{2}$
解析
$-(-99\frac{15}{16})×8$
$=99\frac{15}{16}×8$
$=(100 - \frac{1}{16})×8$
$=100×8 - \frac{1}{16}×8$
$=800 - \frac{1}{2}$
$=799\frac{1}{2}$
$=99\frac{15}{16}×8$
$=(100 - \frac{1}{16})×8$
$=100×8 - \frac{1}{16}×8$
$=800 - \frac{1}{2}$
$=799\frac{1}{2}$
13. $(-0.125)×(-1\frac {2}{7})+(+\frac {1}{5})×(-4\frac {2}{7})+(-\frac {1}{7})×(+\frac {9}{8})$
答案
$-\frac{6}{7}$
解析
$(-0.125)×(-1\frac {2}{7})+(+\frac {1}{5})×(-4\frac {2}{7})+(-\frac {1}{7})×(+\frac {9}{8})$
$=(-\frac{1}{8})×(-\frac{9}{7})+\frac{1}{5}×(-\frac{30}{7})+(-\frac{1}{7})×\frac{9}{8}$
$=\frac{9}{56}-\frac{30}{35}-\frac{9}{56}$
$=(\frac{9}{56}-\frac{9}{56})-\frac{6}{7}$
$=0-\frac{6}{7}$
$=-\frac{6}{7}$
$=(-\frac{1}{8})×(-\frac{9}{7})+\frac{1}{5}×(-\frac{30}{7})+(-\frac{1}{7})×\frac{9}{8}$
$=\frac{9}{56}-\frac{30}{35}-\frac{9}{56}$
$=(\frac{9}{56}-\frac{9}{56})-\frac{6}{7}$
$=0-\frac{6}{7}$
$=-\frac{6}{7}$
14. $(\frac {7}{9}-\frac {5}{6}+\frac {3}{18})×18-1.45×6+3.95×6$
答案
17
解析
$(\frac{7}{9} - \frac{5}{6} + \frac{3}{18}) × 18 - 1.45 × 6 + 3.95 × 6$
$=\frac{7}{9} × 18 - \frac{5}{6} × 18 + \frac{3}{18} × 18 + (-1.45 + 3.95) × 6$
$=14 - 15 + 3 + 2.5 × 6$
$=2 + 15$
$=17$
$=\frac{7}{9} × 18 - \frac{5}{6} × 18 + \frac{3}{18} × 18 + (-1.45 + 3.95) × 6$
$=14 - 15 + 3 + 2.5 × 6$
$=2 + 15$
$=17$
