Wry neck, or torticollis, is a painfully twisted and tilted neck. The top of the head generally tilts to one side while the chin tilts to the other side. This condition can be congenital (present at birth) or acquired. It can also be the result of damage to the neck muscles or blood supply. Wry neck sometimes goes away without treatment.
In the quaternions, 0 is the additive identity. In the ring of functions from R to R, the function mapping every number to 0 is the additive identity. In the additive group of vectors in Rn, the origin or zero vector is the additive identity.
Mathematical beauty. 1  The number 0, the additive identity. 2  The number 1, the multiplicative identity. 3  The number Ï, which is ubiquitous in the geometry of Euclidean space and analytical mathematics (Ï = 3.141...) 4  The number e, the base of natural logarithms, which occurs widely in mathematical analysis (e = 2.718...).