Water has a rotation axis that bisects the H-O-H angle.  Rotation of 180° about this axis gives a molecule indistinguishable from the original.   In this example, n=2 (180 = ³⁶⁰/₂).  Thus, water has a two fold axis of rotation, and the Schoenflies symbol is C₂.

     Chloroform has a rotation axis coincident with the C-H bond.  Rotation of 120° about the C-H bond gives a molecule indistinguishable from the original.   In this example, n=3 (120 = ³⁶⁰/₃).  Thus, chloroform has a three fold axis of rotation, and the Schoenflies symbol is C₃.

     Square planer PtCl₄^2- has four C₂ rotation axis, two coincident with Pt-Cl bonds, and two that bisect Cl-Pt-Cl angles.  More importantly, there is also a C₄ axis perpendicular to the plane of the five atoms.  Rotation of 90° about this axis gives a molecule indistinguishable from the original.   In this example, n=4 (90 = ³⁶⁰/₄).  Thus, PtCl₄^2- has a four fold axis of rotation.