It depends on the system. Some computers use binary, some use hexadecimal, and some use decimal. In binary, a number can’t be smaller than one, meaning it’s only used to represent values greater than zero. In other words, a computer can never hold a negative number in its memory or monitor! Hexadecimal usually represents values from 0-9 as well as A-F (10-15). Decimal is our familiar “base 10” representation of numbers that fits any value from 0-9 and assigns specific symbols for tens (10’s) and units (1’s).