Задание 18

1) $$rac{3}{20} = \frac{3}{2 \cdot 2 \cdot 5} = \frac{3 \cdot 5}{2 \cdot 2 \cdot 5 \cdot 5} = \frac{15}{100} = 0,15$$ Ответ: да, 0,15.

2) $$rac{2}{5} = \frac{2 \cdot 2}{5 \cdot 2} = \frac{4}{10} = 0,4$$

3) $$rac{1}{2} = 0,5$$

4) $$rac{2}{3} = 0,666...$$

5) $$rac{1}{15} = 0,0666...$$

6) $$rac{7}{25} = \frac{7 \cdot 4}{25 \cdot 4} = \frac{28}{100} = 0,28$$

7) $$rac{1}{4} = 0,25$$

8) $$rac{5}{24} = 0,208333...$$

9) $$rac{1}{125} = \frac{1 \cdot 8}{125 \cdot 8} = \frac{8}{1000} = 0,008$$

10) $$rac{7}{20} = \frac{7 \cdot 5}{20 \cdot 5} = \frac{35}{100} = 0,35$$

11) $$rac{11}{50} = \frac{11 \cdot 2}{50 \cdot 2} = \frac{22}{100} = 0,22$$

12) $$rac{5}{6} = 0,8333...$$

13) $$\frac{4}{21} = 0,190476...$$

14) $$\frac{21}{25} = 0,84$$

15) $$3 \frac{3}{4} = 3 + \frac{3}{4} = 3 + \frac{3 \cdot 25}{4 \cdot 25} = 3 + \frac{75}{100} = 3 + 0,75 = 3,75$$

16) $$\frac{3}{12} = \frac{1}{4} = \frac{1 \cdot 25}{4 \cdot 25} = \frac{25}{100} = 0,25$$

17) $$\frac{5}{30} = \frac{1}{6} = 0,1(6)$$ Ответ: нет.

18) $$\frac{3}{125} = \frac{3 \cdot 8}{125 \cdot 8} = \frac{24}{1000} = 0,024$$

19) $$\frac{3}{6} = \frac{1}{2} = 0,5$$

20) $$\frac{13}{26} = \frac{1}{2} = 0,50$$

21) $$1 \frac{1}{2} = 1,50$$

22) $$3 \frac{1}{4} = 3,25$$

23) $$4 \frac{3}{4} = 4,75$$

24) $$2 \frac{1}{3} = 2,(33)$$

25) $$1 \frac{3}{60} = 1 + \frac{3}{60} = 1 + \frac{1}{20} = 1 + 0,05 = 1,05$$

26) $$2 \frac{5}{2} = 2,50$$

27) $$5 \frac{1}{4} = 5,25$$

28) $$\frac{1}{16} = 0,0625$$

29) $$\frac{5}{8} = 0,625$$

30) $$\frac{3}{40} = 0,075$$