@andrewt e.g. https://www.goldennumber.net/music/ ! It's one of those things that just gets repeated around by people who don't really get the maths.
To be fair, "black and white notes" are more accurately 8 notes in a tonal scale (really 7), selected from 13 notes (really 12) in the octave. "Black and white" is just explaining that in the context of C major.