You may have heard the phrase "dressed to the nines"used to mean that someone is dressed in a very elaborate fashion. There seem to be several theories regarding this phrase, none are entirely conclusive.  It's first recorded in the late eighteenth century in poems by Robert Burns. A persistent theory is that the British Army's 99th Regiment of Foot were renowned for their smartness, so much so that the other regiments were constantly trying to emulate them - to equal "the nines". Unfortunately, the story dates from the 1850s, and the phrase is older.

Some speculate it's a reference to the nine Muses of Greek mythology.

Walter Skeat (the editor of the Oxford Etymological Dictionary and the first secretary of the English Dialect Society) once proposed that it could originally have been "dressed to the eyes", which in medireview English would have been "to then eyne"; the phrase could afterwards have mutated by the same principle that caused "a norange" to change to "an orange". But the reverse problem of dating arises here, in that if it were truly medireview in origin one would expect examples to have turned up before Burns' time. So it would appear, at least at present, to be a bit of a mystery.