HEX means hexadecimal system which includes 0-9, A-F.
Conversion is done in the similar manner we convert to binary
HEX stands for Hexidecimal. Which is base 16
Hex means 6 and decimal means 10 so Hexidecimal refers to 16
Normally our numbers are in base 10
We need 10 different digits to express our numbers. that is 0,1,2,3,4,5,6,7,8, and 9
so the base 10 number $$36742 = 3*10^4\;\;+\;\;6*10^3\;\;+\;\;7*10^2\;\;+\;\;4*10^1\;\;+\;\;2*10^0$$
Computers actually work in binary. That is base 2. Each individual signal is either on or off. 0 or 1
So the number
$$\\10011010_2 = 1*2^7\;\;+\;\;1*2^4\;\;+\;\;1*2^3\;\;+\;\;1*2^1 \\\\
= 128+16+8+2=154_{10}\;\;$That means 154 base 10$$$
Now to write everynumber out in base 2 would take for ever. So computer geeks change it to base 16 which is hexidecimal.
For base 16, 16 digits are needed, they are 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F
Now I will try and show you why this is useful. You need to recognise that $$16=2^4$$
Lets look at our base 2 number
$$\\10011010_2$$ I am going to seperate this into groups of 4 like this
$$\\\underbrace{1001}\underbrace{1010}\; base \;2\\\\
now\: 1001_2 = 8+1=9\; $ base 10, and that is also 9 in base 16 \\
and\; 1010_2 = 8+2=10\; $ base 10, and that is A in base 16 \\
so\\
\mbox {10011010 is 9A as a hexidecimal number}$$
Lets just check this. We already discovered that 10011010 base two = 154 base 10
Lets see what 9A base 16 is in base 10
$$\\9A\; (base 16)= 9*16^1+10 = 144+10 = 154\;\;(base 10)\\\\
\mbox{so it has been established that}\\\\
154_{10}=10011010_2=9A_{16}$$
I DO HOPE SOMEONE GETS SOMETHING OUT OF THIS POST BECAUSE IT HAS TAKEN AGES TO WRITE IT.
(I have had lots of interuptions)