Hexadecimal is a “base 16″ numbering system primarily used as an easy-to-read way to represent binary values

As you likely know, computers read/write data in binary at the lowest level. Binary is a “base 2″ numbering system, which means there are only two possible values for each digit. Binary is often compared to a “light switch” because values are either “0″ (off) or “1″ (on). Each binary digit is considered a “bit”.

Because binary is difficult to read and interpret quickly, hexadecimal is often used to simplify and make low-level data easy to deal with. Each hexadecimal digit represents 4 bits (or binary digits). When viewing hex data, viewers often group data digits in pairs of two, because this represents 1 byte of data.

Hexadecimal counts as the following: 0 1 2 3 4 5 6 7 8 9 A B C D E F

Here is a chart showing the Hex/binary values of 0-15.

Now, this is where things get a little more tricky. Obviously, the number system doesn’t just end at “F”. Just like decimal (base 10), when hexadecimal gets to “F”, it adds a digit. So “16″ in decimal is “10″ in hexadecimal, and “17″ in decimal is “11″ in hexadecimal.

An important equation you should familiarize yourself with is how to convert a hexadecimal value to decimal. It is as follows:

Next week we will continue our look at hexadecimal by looking at hex data from the boot sector of an NTFS partition, and also the hex data for certain types of files to show how you can find patterns that will help you identify the type of file, and other interesting attributes about it.