I don't even remember what grade I was in when I learned it, but I've never forgotten it.
The mnemonic for remembering the colors of the rainbow:
It's an obsessive-compulsive person's dream...in the closet.
For me, pink is a light shade of red, I don't wear yellow, and I don't wear purple. I don't wear many light colors at all. Neutrals border the edges of the rainbow.
After white I have beige (since I have long-sleeved beige shirts - see above) and brown. Then after the Red, Orange, Yellow, Green, Blue, Indigo, Violet, of which there was no Yellow or Violet, I have gray and black.
But then with my short sleeves below, since I don't have any beige, I have the white, the rainbow, then brown and black. Since I don't have the beige to transition to brown, the brown has to go at the other end with black.
If I get any beige short-sleeved shirts, the brown would have to move.
Don't ask me why. I don't even know. It's just the way it has to be.
If I have identical colors, v-necks come before crew necks, and crew necks before mock necks before turtlenecks.
Do you organize your clothes by color and/or style?
My shirts always look like this. I didn't make them special for this post.