1800

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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

• Previous  ... Next: Pentagonal Pyramidal Number

Sources

• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $72$