hexadecimal (also known as hex) is base 16, with additional "numbers' of abcdef. So, the entire hex number set is 0123456789abcdef. Hex numbers tend to be denoted with 2 common nomenclatures. Either precede them with a 0x, or append them with a h/H. For example 0x10 or 10H. 0x10 = 16 decimal. The positions are 16^0, 16^1, 16^2, 16^3,... or 0, 16, 256, 4096, ......
HTH.