A16= 1010
B16= 1110
C16= 1210
D16= 1310
E16= 1410
F16= 1510
Its a concise way of expressing numbers. 25510 = FF16. FF = 15*16 + 15. Each digit to the left is 16 times the previous one 40016 = 4*256 = 1024.
In C, C++ and C# numbers are represented as hexadecimal by putting 0x in front. E.g. 0x300 is the same as 768.
Hexadecimal is a very convenient way of showing binary numbers as every 4 binary digits can be shown as one hexadecimal digit.
Glossary:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z10112 = B16

