This article is a part of the "MIDI Reference".
This page describes Hex numbers and how to convert to/from normal numbers.

Hex numbers
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) = 74
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
Hex 74 = (7 * 16) + (4 * 1) = 116
Hex 234 = (2 * 16 * 16) + (3 * 16) + (4 * 1) = 564

 
The basic digits (Notice: A = 10; B = 11 and so on): 
hex	value			hex 	value
0	0			8	 8
1	1			9	 9
2	2			A	10
3	3			B	11
4	4			C	12
5	5			D	13
6	6			E	14
7	7			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.