The first numbering system was base 60.
The decimal system, or base 10, is in mathematics and everyday life, but computers and other electronics need to have simpler (sometimes more complex) systems. Enter, binary.
Step 1: Hex decimal
the numbers 1-20 using hex decimal:
as you can see it uses the letters a-f to repesent real numbers.
so every time you get to nine you go to a and so on. so 100 in hexdecimal is 64.
hex decimal is usely used in video games becauses you can fit big numbers in small space.