Thanksgiving day calculation for year $y, based on Zeller's congruence: 
my $k = $y % 100;
my $j = int($y / 100);
my $d = 28 - (5 + $k + ($k>>2) + ($j>>2) - 2*$j) % 7;

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In reply to Re: Calculating holidays by Anonymous Monk
in thread Calculating holidays by htmanning

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