If you're working on a certification exam such as the CompTIA A+, Network+, or Security+ certification, you might need to review your knowledge of decimal, hexadecimal, and binary. It's basic knowledge, but it's needed and I've found that some people never learned it. Decimal numbers use a base of ten and include the numbers 0 to 9. Hexadecimal numbers use a base of 16 and include the numbers 0 to 9 and the characters A to F. Binary numbers use a base of 2 and include only the numbers 0 and 1. The following table shows how binary is raised to different powers to give different values in a four bit binary number.- Any number raised to the power of 0 is 1 so 2^0 is 1.- Any number raised to the power of 1 is itself so 2^1 is 2- 2 raised to the power of 2 is the same as 2 x 2 (2 squared or4)- 2 raised to the power of 3 is the same as 2 x 2 x 2 (2 cubed or 8) The following table compares each of these number systems side by side. If you plan on taking the A+, Network+ or Security+ exams to give yourself the CompTIA Trio, check out these resources: