The normally used number system is based at 10.
Last digit in a number represents number of "1"; the second last digit represents the number of "10"; the third last digit represents number of "100" (10 * 10) and so on.
35 = (3 * 10) + (5 * 1)
74 = (7 * 10) + (4 * 1)
234 = (2 * 10 * 10) + (3 * 10) + (4 * 1)
Hex values are based at the number 16.
Last digit in a hex number represents number of "1"; the second last digit represents the number of "16"; the third last digit represents number of "256" (16 * 16) and so on.
Hex 35 = (3 * 16) + (5 * 1) = 53 (decimal)
Hex 74 = (7 * 16) + (4 * 1) = 116 (decimal)
Hex 234 = (2 * 16 * 16) + (3 * 16) + (4 * 1) = 564 (decimal)
The basic digits (Notice: A = 10; B = 11 etc.):
| Hex | Decimal |
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 4 |
| 5 | 5 |
| 6 | 6 |
| 7 | 7 |
| 8 | 8 |
| 9 | 9 |
| A | 10 |
| B | 11 |
| C | 12 |
| D | 13 |
| E | 14 |
| F | 15 |
Hex values are often written in groups of two characters (from 00 to FF):
Hex 3F A7 = (3 * 16 * 16 * 16) + (15 * 16 * 16) + (10 * 16) + (7 * 1) = 16295
Tip: Use your Windows Calculator in scientific mode to convert to/from Hex numbers.