Circular Permutation
The number of ways to arrange 
distinct objects along a Circle is
The number is
instead of the usual Factorial 
since all Cyclic Permutations of objects are equivalent because the Circle can be rotated.See also Permutation, Prime Circle- Deltoid Involute
- Deltoid Pedal Curve
- Deltoid Radial Curve
- de Mere's Problem
- Demlo Number
- de Moivre-Laplace Theorem
- de Moivre Number
- de Moivre's Identity
- de Moivre's Quintic
- de Morgan's and Bertrand's Test
- de Morgan's Duality Law
- de Morgan's Laws
- Dendrite Fractal
- Denjoy Integral
- Denominator
- Dense
- Density
- Density (Polygon)
- Density (Sequence)
- Denumerable Set
- Denumerably Infinite
- de Polignac's Conjecture
- Depth (Graph)
- Depth (Size)
- Depth (Statistics)