Elements are conjugate when
for some . Then
for every integer , so exactly when . They therefore have the same order.
The Möbius group consists of the Möbius transformations
of the Riemann sphere, under composition. If , then
Thus is fixed by exactly when is fixed by . Conjugation gives a bijection between their fixed-point sets, so conjugate elements have the same number of fixed points.
A nonidentity Möbius transformation has at most two fixed points because its fixed-point equation is quadratic on the Riemann sphere. If it has only one repeated fixed point, conjugate that point to infinity; the transformation becomes a nontrivial translation , which has infinite order. Consequently every nontrivial finite-order element has two distinct fixed points:
This is fixed points of a finite-order Möbius transformation.