I am a Math Geek
Wednesday, July 9, 2008

It's true, I confess.  On Sunday, we played Mexican Train with my aunt and uncle, which is a game of dominoes.  Mexican Train uses a set of "double twelve" dominoes (I think that's the minimum; their set went up to 15).  At home, I have a set of "double six" dominoes, but I remembered seeing in my set the hexagonal centerpiece similar to the one used in Mexican Train.  So today I played a miniature game of Mexican Train with my mom, using what pieces we had available.  It was a very short game.  Curious, I felt compelled to calculate the mathematical formula that describes how many dominoes belong to a set.

If anyone cares (and I can't imagine who would), the formula is:


where n represents the greatest number of spots in the set.  So a set that goes up to six spots contains 28 dominoes (1+2+3+4+5+6+7), and a set with twelve spots has 91 pieces.

If you're wondering why it's n+1 instead of just n, it's because dominoes have "blanks" (zeros).

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— Deitrich Conhoeffer