An hexadecimal number (hex number) has a base (radix) of 16 whilst a decimal system of notation has a base of 10.

• The familiar decimal system of notation uses nine symbols 0 – 9. It then adds columns to the right to denote 10’s, 100’s etc.
• A hexadecimal system of notation uses sixteen symbols, the symbols 0–9 are used to represent values zero to nine, and A, B, C, D, E, F (or a, b, c, d, e, f) are used to represent values from ten to fifteen. Further columns are added on the right to denote 16’s, 256’s etc.
• A hexadecimal triplet is a six-digit, three-byte hexadecimal system of notation used in programming and software applications (graphic design, web development, photography) to represent colours. The bytes represent the red, then green and then blue components of a colour.
• Each byte represents a number in the range 00 to FF in hexadecimal notation (0 to 255 in decimal notation).
• The hash symbol (#) is used to indicate hex notation.
• Red = #FF0000
• Yellow = #FFFF00
• Green = #00FF00
• Cyan = 00FFFF
• Blue = #0000FF
• Magenta = #FF00FF
• The sequence of hexadecimal values between 1 and 16 = 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E and F.
• The sequence of hexadecimal values between 17 and 32 = 10,11,12,13,14,15,16,17,18,19,1A,1B,1C,1D,1E and 1F.