1800

Number
$1800$ (one thousand eight hundred or eighteen hundred) is:


 * $2^3 \times 3^2 \times 5^2$


 * The $15$th pentagonal pyramidal number after $1$, $6$, $12$, $40$, $75$, $126$, $196$, $288$, $405$, $550$, $726$, $936$, $1183$, $1470$:
 * $1800 = \ds \sum_{k \mathop = 1}^{15} \dfrac {k \paren {3 k - 1} } 2 = \dfrac {15^2 \paren {15 + 1} } 2$


 * The product of the number of edges, edges per face and faces of a regular dodecahedron.
 * $30 \times 12 \times 5$


 * The product of the number of edges, edges per face and faces of a regular icosahedron.
 * $30 \times 20 \times 3$

Also see

 * Product of Number of Edges, Edges per Face and Faces of Regular Dodecahedron
 * Product of Number of Edges, Edges per Face and Faces of Regular Icosahedron