The Eleven ==== Grateful Dead
This song is all about math - and psychedelic, hippie nonsense. And odd musical time signatures. Common time in music is sometimes also called 4/4 - that’s 4 beats in 1 measure. The Eleven is an odd time signature known as 11/12. They drop the last beat. So instead of the beat going 1234, 1234, 1234 it goes like this: 123, 456, 789, 10 11. That drives the beat really fast and the Dead would morph common time into The Eleven and back again over the course of, usually, about 10 minutes. Lots of fun.