My goodness, Ruby has come a long way... 12 times as fast as I made the 
original post.  On a Mac Mini I got last year about summer, running Ruby 
2.0, I got 705016 iterations per second:


ruby cal.rb
55

Ruby 2.0.0 patch 247 on x86_64-darwin12.4.0
It took 1.418407 seconds to run. 705016 iterations per second.

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