An angle of 1º can be divided into 60 equal parts. 

Each of these parts is known as 1 minute (1').

So 60' = 1º

An angle of 1' can be divided into 60 equal parts. 

Each of these parts is known as 1 second (1").

So 60" = 1'    and   3600" = 1º

Example

Convert 13.49º  into an angle in degrees, minutes and seconds.

Answer

Just look at the part after the decimal point i.e. 0.49º

Use a calculator to work out 0.49 x 60 = 29.4

13.49º = 13º 29.4'

Now again look at the part after the decimal point in 29.4' i.e. 0.4'

Use a calculator to work out 0.4 x 60 = 24"

So 13.49º = 13º 29' 24"