Bài 1:

a)$\frac{1}{10}$ =0,1

$\frac{1}{100}$ =0,01 

$\frac{1}{1000}$ =0,001

b)$\frac{84}{10}$ =$\frac{42}{5}$ =8,4

$\frac{255}{10}$=$\frac{51}{2}$ =25,5

$\frac{6453}{1000}$=6,453

Bài 2:

a)1$\frac{9}{10}$=$\frac{19}{10}$ 

2$\frac{66}{100}$=$\frac{266}{100}$ =$\frac{133}{50}$ 

3$\frac{72}{100}$=$\frac{372}{100}$ =$\frac{93}{25}$ 

b)85$\frac{2}{10}$ =$\frac{852}{10}$ =$\frac{426}{5}$ 

30$\frac{2}{100}$=$\frac{3002}{100}$ =$\frac{1501}{50}$ 

54$\frac{73}{1000}$=$\frac{54073}{1000}$ 

Bài 3:

a)17,425⇒17,4250

0,24⇒0,2400

40,05⇒40,0500

b)38,4⇒38,4000

90,02⇒90,0200

10,067⇒10,0670

Bài 4:

a)x=1

b)x=2

c)x=4

d)x=0

e)x=3

g)x=6

Bài 5:

4,785<4,875

1,79=1,7900

72,99>72,989

81,02>81,018

$\frac{5}{100}$=0,05

24,518<24,52

90,051>90,015

8,101<8,10101

67>66,999

$\frac{8}{100}$=0,08

Bài 6:

a)7,925 ; 9,725 ; 9,75 ; 9,752

b)86,077 ; 86,707 ; 86,77 ; 87,67

c)$\frac{5}{4}$ ;$\frac{3}{2}$ ; 2,2 ; $\frac{9}{4}$ 

Bài 7:

Các số đó là: 0,35 ; 0,53 ; 3,05 ; 3,50 ; 5,03 ; 5,30