Hexadecimal

• Binary numbers are difficult for programmers to work with.
• If we're building a web-page, then chances are we're going to want to use colour.
• In general computers use the RGB colour model, where any colour we need is made up by additive mixing Red, Green and Blue.
• The value of RGB colours ranges from 0,0,0 up to 255,255,255.

Here's a colour that is represented as R-159, G-028, B-173.

• Coders use Hexadecimal as it's easy to convert it to binary, but it is more succinct.
• When counting in Hexadecimal, we use the letters A-F after reaching 9.
• 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F
• Normally we would use a table to aid in the conversion.

• We can take a binary number, such as 10101101.
• Split it up into nibbles - 1010 1101
• Convert each to Hex - AD

• With experience, you'll not need a table, as you'll come to recognise the hex equivalent for each nibble.
• However, if you don't have a conversion table or can't remember the values, you can convert between binary and hex, by using denary as a middle step.
• Lets start with the binary number 01011101
• Split it into nibbles - 0101 1101
• Convert to denary - 1*1 + 0*2 + 1*4 + 0*8 and = 1*1 + 0*2 + 1*4 + 1*8
• So we get - 5 and 13
• Now convert to Hex - 5 and D
• So the Hex is 5D

• Converting hex to binary is a fairly similar process. We just need to do the denary conversion in between.
• Take the number 9E
• Split it up 9 and E
• Convert each to denary 9 and 14
• Then convert each to binary 1*8 + 0*4 + 0*2 + 1*1 and 1*8 + 1*4 + 1*2 + 0*1
• Which makes 1001 and 1110
• Which together becomes 10011110