A gentle 
introduction to hexadecimal (base 16).
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:
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 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.
The benefit of using hexadecimal instead of binary, where each digit is a power of two, is that it is much shorter to write, but still lets us easily determine the value of specific bits:
Another popular base in the computer world is octal – base 8. It's more compact than binary (since each digit is a power of 8), but less compact than either decimal or hexadecimal.