# Hex

Updated: 07/06/2021 by Computer Hope

Hex may refer to any of the following:

1. Alternatively called base-16 or hex, the hexadecimal numbering system uses combinations of 16 character digits to represent numbers. Hexadecimal uses all ten numbers in the decimal system (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) and letters A through F. For example, "computer hope" in hexadecimal becomes "636f6d707574657220686f7065".

Anyone who has designed a web page has encountered hexadecimal value when doing colors. For example, to create red text use the HTML color code #FF0000, which translates to 255 red, 0 green, and 0 blue in hexadecimal.

## What are numbers with a "0x" prefix?

Numbers with a "0x" (zero and x) prefix indicate the number shown is a hexadecimal number. For example, "0xCD" is the decimal equivalent of "205." By having "0x" in front of "CD," the reader knows they're dealing with a hexadecimal number and not something else, like the CD acronym in this example.

Note

When hexadecimal uses the "0x" prefix, "0x" is only an indicator of the type of number being represented. In other words, with "0xCD," the "CD" is the hexadecimal number, and "0x" is ignored.