Hexadecimals
A Hexadecimal Number is based on the number
16

This is 2×16×16 + 14×16 + 6 + 10/16 + 3/(16×16)
Read below to find out why

Numbers can be placed to the left
or right of the point, to indicate values greater than one
or less than one:

The number just to the left of the point
is a whole number, we call this place units.
As we move left, every number place gets 16
times bigger. 



The first digit on the right of the point means sixteenths
(1/16).
As we move further right, every number place
gets 16 times smaller (one sixteenth as big). 
16 Different Values
The Hexadecimal numbers look the same as the decimal numbers up to 9, but then there are the letters ("A',"B","C","D","E","F") in place of the decimal numbers 10 to 15:
Decimal: 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
Hexadecimal: 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
A 
B 
C 
D 
E 
F 
So a single Hexadecimal digit can show 16 different values instead of the normal 10.
Definition of Hexadecimal

The word "Hexadecimal" means "based on 16"
(From Greek hexa: "six" and Latin decima: "a tenth part"). 
Examples
Example 1: What is 2E6 (Hexadecimal)?
 The "2" is in the "16×16" position, so that means 2×16×16
 The "E" is in the "16" position, so that means 14×16
 The "6" is in the "Units" position so that means 6.
 Answer: 2E6 = 2×16×16 + 14×16 + 6 (=742 in Decimal)
Example 2: What is 2.3 (Hexadecimal)?
 On the left side is "2", that is the whole number
part.
 The 3 is in the "sixteenths" position, meaning "3
sixteenths", or 3/16
 So, 2.3 is "2 and 3 sixteenths" (=2.1875 in Decimal)
