Interesting with these "rhymes". We learned it another way. The colours of the rainbow are known by everyone - and they constitute numbers 2 - 7. It is then an easy matter to remember that black is zero (no light) and that white is nine (most light). Brown (1) fits nicely between blk and rd and so does grey (8) between vl and wt.
So where was this Violet when I was in high school?
I can't remember what they taught us, but I do remember ROYGBIV (pronounced roy-gee-biv) from my optics classes and the rest is always easy to fill in.
I daren't post the version I learnt in school. It was pretty horrible - rapes and virgins featured in it. I hadn't given it any thought in a long time until this thread triggered the memory. Perhaps it should stay forgotten!