Polyominos

Date: 08/11/99 at 03:30:29
From: Markee Guest
Subject: Math involving squares

What is the definition of a polyomino used in relation to squares? I 
looked in Merriam-Webster dictionary and tried different geometry 
sites and had no luck.

Date: 08/11/99 at 14:29:13
From: Doctor Rob
Subject: Re: Math involving squares

Thanks for writing to Ask Dr. Math.

I think you know what a domino is. An abstract domino is a rectangle 
that is formed by joining two squares together along a side.

If you were to join three squares together along sides, you would get 
an object you could call a tri-omino (tri-: three; di-: two) or 
triomino. There are two different ways to do this, one in which the 
three squares are in a row, forming a 3-by-1 rectangle, and one in 
which they form an L or V shape.

If you join four squares together along sides, you would get a 
tetromino (tetra-: four). There are five different ways to do that. 
Try to find them all.

You can continue this for larger and larger numbers of squares, 
forming pentominos, hexominos, and so on.

The entire set of objects you get (including the monomino) is called 
polyominos. (Two polyominos are not considered different if one is 
congruent to the other, including flipping it over.)

- Doctor Rob, The Math Forum
  http://mathforum.org/dr.math/