Rubik's Clock
A puzzle consisting of 18 small clocks. There are 
possible configurations, although not all arerealizable.
References
Dénes, J. and Mullen, G. L. ``Rubik's Clock and Its Solution.'' Math. Mag. 68, 378-381, 1995. Zeilberger, D. ``Doron Zeilberger's Maple Packages and Programs: RubikClock.'' http://www.math.temple.edu/~zeilberg/programs.html.
- Schönflies Symbol
- Schönflies Theorem
- Scientific Notation
- s-Cluster
- Score Sequence
- Screw
- Screw Theorem
- Scruple
- Sea Horse Valley
- Searching
- Search Tree
- Seashell
- Secant
- Secant Line
- Secant Method
- Secant Number
- Sech
- Second
- Second Curvature
- Second Derivative Test
- Second Fundamental Tensor
- Sectional Curvature
- Section (Graph)
- Section (Pencil)
- Section (Tangent Bundle)