I also did this. Helps remember the order of the colours (red, green, blue) in the hexadecimal notation if it doesn't come naturally. FWIW, I've been using this

I also did this. Helps remember the order of the colours (red, green, blue) in the hexadecimal notation if it doesn't come naturally. FWIW, I've been using this notation in CSS for over 10 years and I still couldn't visualise most of the colours except the most obvious ones (e.g. FF0000). I wonder if it comes naturally to some people.