Cigarettes
It is possible to place 7 cigarettes in such a way that each touches the other if 
(Gardner 1959,p. 115).
References
Gardner, M. The Scientific American Book of Mathematical Puzzles & Diversions. New York: Simon and Schuster, 1959.
- Chordal
- Chordal Theorem
- Chow Coordinates
- Chow Ring
- Chow Variety
- Christoffel-Darboux Formula
- Christoffel-Darboux Identity
- Christoffel Formula
- Christoffel Number
- Christoffel Symbol of the First Kind
- Christoffel Symbol of the Second Kind
- Chromatic Number
- Chromatic Polynomial
- Chu Identity
- Church's Theorem
- Church's Thesis
- Church-Turing Thesis
- Chu Space
- Chu-Vandermonde Identity
- Chvátal's Art Gallery Theorem
- Chvátal's Theorem
- ci
- Ci
- Cigarettes
- Cin