Copy LinkCopied!Hexadecimal

We are used to count in a decimal system.

This is a system where the amount of unique numerals is ten, starting at 0 until 9. To count more than the tenth number (which is 9), we need to use 2 or more of the existing numerals.

In decimal, the digits are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

We call this a system with a "base 10"

To reach the number after 9, we need to associate two previous numerals: 0, and 1: 10, 11, ..., 42, ...

Hexadecimal is a "base 16" system, where the digits are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.

Decimal	Hexadecimal
0	0
1	1
2	2
3	3
4	4
5	5
6	6
7	7
8	8
9	9
10	A
11	B
12	C
13	D
14	E
15	F

If we want to represent 16 in decimal, we need to add two more digits: 1, and 0. It's very unintuitive! But you get used to it.

Decimal	Hexadecimal
16	10
17	11
18	12
19	13
20	14
...	...
160	A0
161	A1
176	B0

Copy LinkCopied!How to get the decimal number from a hexadecimal number?

1. Split the number in digits
2. For each digit, convert it do decimal (A to 10, B to 11, C to 12, and so on)
3. Counting from the right, multiply each digit by the 16 raised to the power of its position. So the first digit is 16^0, the second digit is 16^1, and so on.
4. Add all the products together

Let's take C2:

digit	power 16
C	12 X 16^1	=	192
2	2 X 16^0	=	2
	total	=	194

Let's take FF:

digit	power 16
F	15 X 16^1	=	15
F	15 X 16^0	=	240
	total	=	255

Copy LinkCopied!What does any of this has to do with colors?

In regular programming, hexadecimal is most often encountered to encode colors.

For example

• #FF0000 is red.
• #00FF00 is green.
• #0000FF is blue.

The format is #RRGGBB, where RR, GG, and BB are hexadecimal values for the red, green, and blue channels, respectively.

This is because the hexadecimal color encoding takes two digits to represent each color channel: in the first example,FF is the amount of red in the color, and 00 is the amount of green in the color. FF is equal to 255, so that is equivalent to writing rgb(255, 0, 0).

Some hexadecimal notations add two digits to represent alpha: #RRGGBBAA, where 00 is completely transparent, and FF is completely opaque.

Finally, in some languages, it is accepted to use the #RGB format, forgeting the 0 for small numbers.