A number system with 16 elements present, i.e. base 16. These elements are the numbers 0 to 9 and the letters A to F. Therefore 1010 = A16, 1110 = B16, etc., where the subscript indicates the decimal or hexadecimal system. Hexadecimal is often used in computer systems, for example for 16-bit arithmetic, for describing character-set codes, or for specifying colours in HTML pages.