Yes, we can represent all decimals on the number line.
We know that, 2.3 is greater than 2, but less than 3. So, divide the unit length between 2 and 3 into 10 equal parts and take 3 parts as shown below:

Thus, A represents 2.3 on the number line. There are 2 ones and 3 tenths in 2.3 and it will lie between 2 and 3 on the number line.

Given, length of Ravi's pencil = 7 cm 5 mm
and length of Raju's pencil = 8 cm 3 mm
We know that, 10 mm = 1cm
\(\therefore\)1 mm = \(\frac { 1 }{ 10 } \) cm or one-tenth cm = 0.1 cm
Now, length of Ravi's pencil = 7 cm 5 mm
= 7 cm and 5 tenths cm
= 7cm + \(\frac { 5 }{ 10 } \) cm
= 7 crn+ 0.5 cm = 7.5 cm
and length of Raju's pencil = 8 cm 3 mm
= 8 cm and 3 tenths cm
=8 cm + \(\frac { 3 }{ 10 } \)cm=8 cm + 0.3 cm = 8.3 cm

Money spent for Mathematics book = Rs.30.55 and money spent for Science book = Rs.20.54
ஃ Total amount spent = 30.55 + 20.54 = ~ 51.09

We have, 2.29 - 0.95
Now, 
\(\quad Ones\quad Tenths\quad Hundreaths\\\quad\quad2\quad\quad\quad\quad2\quad\quad\quad\quad\quad9\\-\quad0\quad\quad\quad\quad9\quad\quad\quad\quad\quad5\\\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\\\quad\quad1\quad \quad\quad\quad3\quad\quad\quad\quad\quad4\\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\)
\(\therefore\)     2.9 - 0.95 = 1.34

66.02

=

Decimals in words are given below:
We have, 0.03 = Zero point zero three

Seven point six two

162 mm = 16.2 cm

We have, 0.6=0+\(\frac { 6 }{ 10 } =\frac { 6 }{ 10 } \)
Lowest form=\(\frac { 6\div 2 }{ 10\div 2 } =\frac { 3 }{ 5 } \) [\(\because\) HCF of 6 and 10 = 2]
\(\therefore\) Fraction of 0.6=\(\frac{6}{10} \) and lowest form =  \(\frac{3}{5 } \)

Six hundreds point eight = 600.8

Seven-tenths=\(7\times \frac { 1 }{ 10 } =\frac { 7 }{ 10 } =0.7\)

Here, 270.24 + 12.52+ 1.5 can be written as

270.24 + 12.52 + 1.50 = 284.26

Here 280.64 + 25.5 + 28 can be written as

280.64 + 25.5 + 28 = 334.14

Rs 634.50

19 km 48 m = 19 km + 48 m
=19 km + \(\frac { 48 }{ 1000 } km\)
= 19 km + 0.048 km
= 19.048 km

\(4.50=4+\frac { 50 }{ 100 } =4+\frac { 1 }{ 2 } =4\frac { 1 }{ 2 } =\frac { 9 }{ 2 } \)