The hexadecimal system is a way of expressing integers using the base 16. It is in contrast to the decimal system, which uses base 10. Counting to “$10$” in hexadecimal looks like
\[0, 1, 2, \ldots, 8, 9, A, B, C, D, E, F, 10.\]But of course, $10$ in hexadecimal is actually $16$ in decimal, and $A$ in hexadecimal is $10$ in decimal. For example, here are the first 30 integers in both hexadecimal and decimal form.
| Hexadecimal | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
|---|---|---|---|---|---|---|---|---|---|---|
| Decimal | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| Hexadecimal | A | B | C | D | E | F | 10 | 11 | 12 | 13 |
|---|---|---|---|---|---|---|---|---|---|---|
| Decimal | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 |
| Hexadecimal | 14 | 15 | 16 | 17 | 18 | 19 | 1A | 1B | 1C | 1D |
|---|---|---|---|---|---|---|---|---|---|---|
| Decimal | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 |