A gentle gentle 
introduction to hexadecimal (base 16).
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Decimal numbers
In our standard decimal system each digit (which can be 0,1,2,3,4,5,6,7,8,9) in a number represents a power of ten in that place:
Hexadecimal numbers
The hexidecimal (base 16) system is similar, except that each digit represents a power of 16 in that place.
Because a digit can have values greater than 9, there are additional digit values symbols allowed in hex:
- A (10), B (11), C (12), D (13), E (14) and F (15)
...
To convert a decimal number to hex, you remove multiples of those powers of 16 as shown below.
Binary numbers
In the binary (base 2) system, each digit is a power of two, and the digits are just 0 and 1.
It's easy to translate a hexadecimal number into binary because you can decompose each hex digit into its 4 bits.
The benefit of using hexadecimal instead of binary, is that it hex is much shorter to write, but still lets us easily determine the value of specific bits:.
Octal numbers
Another popular base in the computer world is octal – (base 8) where each digit is a power of 8, and digits are 0, 1, 2, 3, 4, 5, 6, 7.
Octal is more compact than binary, but less compact than either decimal or hexadecimal.