For nine or ten years, I sang with a Men's Chorus. We sang 95% of the songs, learning them by ear with nary a page of sheet music in sight. Then insidiously, the Chorus became a Choir. We still sing the same way, and the arrangements haven't changed. We still rarely sing from sheet music and the arrangements evolve over time not being hamstrung by sheets of paper. I still think we're a Chorus.
None of this has anything to do with numbers. Except maybe musical numbers.

There isn't a mathemetician in the group.

Jerry