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一、填空题
1. $(-45)+39+(-55)=$
2. $198-37-63=$
3. $\frac{5}{9}+1\frac{5}{7}+\frac{4}{9}+(-\frac{5}{7})=$
4. $99×7.4+7.4=$
5. $(\frac{2}{3}-\frac{4}{7})×21=$
6. $(-1800)÷25÷4=$
7. $-8×4×(-0.125)=$
8. 一题多解 $9\frac{8}{9}×(-9)=$
1. $(-45)+39+(-55)=$
-61
2. $198-37-63=$
98
3. $\frac{5}{9}+1\frac{5}{7}+\frac{4}{9}+(-\frac{5}{7})=$
2
4. $99×7.4+7.4=$
740
5. $(\frac{2}{3}-\frac{4}{7})×21=$
2
6. $(-1800)÷25÷4=$
-18
7. $-8×4×(-0.125)=$
4
8. 一题多解 $9\frac{8}{9}×(-9)=$
-89
答案
1. -61
2. 98
3. 2
4. 740
5. 2
6. -18
7. 4
8. -89
解析：解法一 $9\frac{8}{9}×(-9) = (9+\frac{8}{9})×(-9)=9×(-9)+\frac{8}{9}×(-9)=-81+(-8)=-89.$
解法二 $9\frac{8}{9}×(-9) = (10-\frac{1}{9})×(-9)=10×(-9)-\frac{1}{9}×(-9)=-90+1=-89.$
2. 98
3. 2
4. 740
5. 2
6. -18
7. 4
8. -89
解析：解法一 $9\frac{8}{9}×(-9) = (9+\frac{8}{9})×(-9)=9×(-9)+\frac{8}{9}×(-9)=-81+(-8)=-89.$
解法二 $9\frac{8}{9}×(-9) = (10-\frac{1}{9})×(-9)=10×(-9)-\frac{1}{9}×(-9)=-90+1=-89.$
二、计算题
9. $(-6) ÷ (+0.25) ÷ (-4)$
10. $(-\frac{1}{9} - \frac{1}{6} - \frac{1}{18}) × 36$
11. $-9\frac{22}{23} × (-46)$
12. $\frac{6}{7} × 3 + (-\frac{2}{7}) × 3 + \frac{3}{7} × 3$
13. $-\frac{1}{42} ÷ (\frac{1}{6} - \frac{3}{14} + \frac{2}{3} - \frac{2}{7})$
14. $\frac{1}{2} + \frac{1}{6} + \frac{1}{12} + \frac{1}{20} + \frac{1}{30} + \frac{1}{42}$
15. $\frac{4}{5} × (-\frac{5}{13}) - (-\frac{3}{5}) × (-\frac{5}{13}) - \frac{5}{13} × (-1\frac{3}{5}) + \frac{5}{13} × (-\frac{2}{5})$
9. $(-6) ÷ (+0.25) ÷ (-4)$
10. $(-\frac{1}{9} - \frac{1}{6} - \frac{1}{18}) × 36$
11. $-9\frac{22}{23} × (-46)$
12. $\frac{6}{7} × 3 + (-\frac{2}{7}) × 3 + \frac{3}{7} × 3$
13. $-\frac{1}{42} ÷ (\frac{1}{6} - \frac{3}{14} + \frac{2}{3} - \frac{2}{7})$
14. $\frac{1}{2} + \frac{1}{6} + \frac{1}{12} + \frac{1}{20} + \frac{1}{30} + \frac{1}{42}$
15. $\frac{4}{5} × (-\frac{5}{13}) - (-\frac{3}{5}) × (-\frac{5}{13}) - \frac{5}{13} × (-1\frac{3}{5}) + \frac{5}{13} × (-\frac{2}{5})$
答案
9. 6
10. -12
11. 458
12. 3
13. $-\frac{1}{14}$
14. $\frac{6}{7}$
15. $-\frac{1}{13}$
10. -12
11. 458
12. 3
13. $-\frac{1}{14}$
14. $\frac{6}{7}$
15. $-\frac{1}{13}$
