a) \(\dfrac{1}{10}=0,1\)

\(\dfrac{1}{100}=0,01\)

\(\dfrac{1}{1000}=0,001\)

\(\dfrac{1}{10000}=0,0001\)

b) \(\dfrac{84}{10}=8,4\)

\(\dfrac{225}{100}=2,25\)

\(\dfrac{6453}{100}=64,53\)

\(\dfrac{25789}{10000}=2,5789\)

\(a.\)

\(0.3=\dfrac{3}{10}\)

\(0.72=\dfrac{72}{100}\)

\(1.5=\dfrac{15}{10}\)

\(9.347=\dfrac{9347}{1000}\)

\(b.\)

\(\dfrac{1}{2}=\dfrac{5}{10}\)

\(\dfrac{2}{5}=\dfrac{4}{10}\)

\(\dfrac{3}{4}=\dfrac{75}{100}\)

\(\dfrac{6}{25}=\dfrac{24}{100}\)

a) \(0,3=\dfrac{3}{10}\)

\(0,72=\dfrac{72}{100}\)

\(1,5=\dfrac{15}{10}\)

\(9,347=\dfrac{9347}{1000}\)

b) \(\dfrac{1}{2}=\dfrac{5}{10}\)

\(\dfrac{2}{5}=\dfrac{4}{10}\)

\(\dfrac{3}{4}=\dfrac{75}{100}\)

\(\dfrac{6}{25}=\dfrac{24}{100}\)

`a,3/10=0,3`

`3/100=0,03`

`4 25/100=4 1/4=4,25`

`2002/1000=2,002`

`b,1/4=0,25`

`3/5=0,6`

`7/8=0,875`

`1 1/2=1,5`

a) Biểu diễn bằng số thập phân: 0,3; 0,03; 4,25; 2,002

b) Biểu diễn bằng số thập phân: 

\(\dfrac{1}{4}=\dfrac{25}{100}=0,25\\ \dfrac{3}{5}=\dfrac{6}{10}=0,6\\ \dfrac{7}{8}=\dfrac{875}{1000}=0,875\\ 1\dfrac{1}{2}=\dfrac{3}{2}=\dfrac{15}{10}=1,5\)

a) \(\dfrac{3}{10}=0.3\)

\(\dfrac{3}{100}=0.03\)

\(4\dfrac{25}{100}=4.25\)

\(\dfrac{2002}{1000}=2.002\)

b) \(\dfrac{1}{4}=0.25\)

\(\dfrac{3}{5}=0.6\)

\(\dfrac{7}{8}=0.875\)

\(1\dfrac{1}{2}=1.5\)

a: \(1\dfrac{9}{10}=1,9\)

\(2\dfrac{66}{100}=2,66\)

\(3\dfrac{72}{100}=3,72\)

\(4\dfrac{999}{1000}=4,999\)

b: \(8\dfrac{2}{10}=8,2\)

\(36\dfrac{23}{100}=36,23\)

\(54\dfrac{7}{100}=54,07\)

\(12\dfrac{254}{1000}=12,254\)

\(\dfrac{{21}}{{10}} = 2,1;\dfrac{{ - 35}}{{10}} =  - 3,5;\dfrac{{ - 125}}{{100}} =  - 1,25;\)\(\dfrac{{ - 89}}{{1000}} =  - 0,089\)

1.

\(\dfrac{{ - 5}}{{1000}} =  - 0,005;\dfrac{{ - 798}}{{10}} =  - 79,8\).

Số đối của -0,005 là 0,005.

Số đối của -79,8 là 79,8.

2.

\( - 4,2 =  - \dfrac{{42}}{{10}}; - 2,4 = \dfrac{{ - 24}}{{10}}\).

\(a,=\dfrac{1}{10}+\dfrac{2}{10}+\dfrac{3}{10}+\dfrac{4}{10}+\dfrac{5}{10}+\dfrac{6}{10}+\dfrac{7}{10}+\dfrac{8}{10}+\dfrac{9}{10}=\dfrac{45}{10}=4,5\\ b,=\dfrac{4}{5}\times\left(\dfrac{3}{8}+\dfrac{5}{8}-\dfrac{7}{8}\right)\times2=\dfrac{8}{5}\times\dfrac{1}{8}=\dfrac{1}{5}=0,2\)

a) Rút gọn các phân số về tối giản, ta được:
\(\dfrac{1}{10}\)+\(\dfrac{2}{10}\)+\(\dfrac{3}{10}\)+\(\dfrac{4}{10}\)+\(\dfrac{5}{10}\)+\(\dfrac{6}{10}\)+\(\dfrac{7}{10}\)+\(\dfrac{8}{10}\)+\(\dfrac{9}{10}\)= kết quả là \(\dfrac{45}{10}\) ra số thập phân = \(4,5\)
b) \(\dfrac{4}{5}\) \(\times\) \(\left(\dfrac{3}{8}+\dfrac{5}{8}-\dfrac{7}{8}\right)\) = \(\dfrac{4}{5}\times\dfrac{1}{8}\) = \(\dfrac{4}{40}=\dfrac{1}{10}\)\(\div\dfrac{1}{2}\)
 = \(\dfrac{2}{10}=0,2\)

\(\dfrac{15}{10}=1,5;\dfrac{35}{100}=0,35;\dfrac{107}{100}=1,07\)

\(\dfrac{22109}{1000}=22,109;\dfrac{14}{5}=\dfrac{28}{10}=2,8;\dfrac{920}{1000}=0,92\)

\(\dfrac{138}{100}=1,38;\dfrac{2007}{10}=200,7;\dfrac{1}{1000}=0,001\)

1,5

0,35

1,007

22,109

2,8

0,92

1,38

200,7

0,001

a) 7/5 =1,4

3/8 =0,375

16/25 =0,64

=1,4

=0,375

=0,64

= 14/10

= 375/1000

= 64/100