page_title: Regular icosahedron
section_title: Toys and games
hierarchical_section_title: Regular icosahedron / Uses and natural forms / Toys and games
caption_attribution_description: dice
context_page_description: In geometry, a regular icosahedron is a convex polyhedron with 20 faces, 30 edges and 12 vertices. It is one of the five Platonic solids, and the one with the most sides.
  It has five equilateral triangular faces meeting at each vertex. It is represented by its Schläfli symbol {3,5}, or sometimes by its vertex figure as 3.3.3.3.3 or 3⁵. It is the dual of the dodecahedron, which is represented by {5,3}, having three pentagonal faces around each vertex.
  A regular icosahedron is a strictly convex deltahedron and a gyroelongated pentagonal bipyramid and a biaugmented pentagonal antiprism in any of six orientations.
  The name comes from Greek εἴκοσι, meaning 'twenty', and ἕδρα, meaning 'seat'. The plural can be either "icosahedrons" or "icosahedra".
context_section_description: Icosahedral dice with twenty sides have been used since ancient times.
  In several roleplaying games, such as Dungeons & Dragons, the twenty-sided die (d20 for short) is commonly used in determining success or failure of an action. This die is in the form of a regular icosahedron. It may be numbered from "0" to "9" twice (in which form it usually serves as a ten-sided die, or d10), but most modern versions are labeled from "1" to "20".
  An icosahedron is the three-dimensional game board for Icosagame, formerly known as the Ico Crystal Game.
  An icosahedron is used in the board game Scattergories to choose a letter of the alphabet. Six letters are omitted (Q, U, V, X, Y, and Z).
  In the Nintendo 64 game Kirby 64: The Crystal Shards, the boss Miracle Matter is a regular icosahedron.
  Inside a Magic 8-Ball, various answers to yes–no questions are inscribed on a regular icosahedron.
caption: Twenty-sided die
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