(base 16). In the octal system we only need the symbols 0, 1, 2, 3, 4, 5, 6, 7,
whereas hexadecimal uses 16 symbols. In this base 16 system, we customarily
use 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F. As 10 corresponds to the letter A,
the number 394 is represented in hexadecimal as 18A. It’s as easy as ABC,
which bear in mind, is really 2748 in decimal!

the condensed idea

Writing numbers down