Decagonal a. : Pertaining to a decagon; having ten sides.

Example:
What is the volume formula for a Decagonal prism?

Taxonomy
decagonal number, s-2, free encyclopedia, n2, s-4, search, formula, 3n, square, Dn, alternate, 2-n, sqrt, Personal tools, Interaction, Toolbox, Languages, non-profit organization.

Defination from the web:
decagonal numbers are ... The decagonal number for n can also be calculated by adding the square of n to thrice the (n - 1)th pronic number, or to put it algebraically, Dn ...