1.5 Math for a Digital Age
1.5.6 The base 16 (hexadecimal) number system

The Base 16, or hexadecimal, number system is used frequently when working with computers, since it can be used to represent binary numbers in a more readable form. The computer performs computations in binary, but there are several instances when the computer binary output is expressed in hexadecimal to make it easier to read. The most common way for computers and software to express hexadecimal output is using "0x" in front of the hexadecimal number. Whenever "0x" is seen, the number that follows is a hexadecimal number. For example, 0x1234 means 1234 in Base 16.

Base 16 uses 16 characters to express numerical quantities. These characters are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F. An "A" represents the decimal number 10, "B" represents 11, "C" represents 12, "D" represents 13, "E" represents 14, and "F" represents 15. Examples of hexadecimal numbers are 2A5F, 99901, FFFFFFFF, and EBACD3. A number such as B23CF (hexadecimal) = 730063 (decimal).

The traditional conversion between decimal and hexadecimal is outside the scope of this course. However, later in this chapter some shortcuts for conversion to any base, including decimal and hexadecimal, will be discussed.