I swear I am not making this up:

Found in oneworld Sweepstakes Term & Conditions:

"Should a winner reside in Canada, he or she will be required to successfully complete a time-limited arithmetical skill-testing question."

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And as tummyg pointed out in the AA thread:

"Each time you fly American Airlines, British Airways, Canadian Airlines, Cathay Pacific, Qantass, Finnair or Iberia on an eligible ticket* between October 1, 1999 and December 31, 1999, you will be automatically entered into a drawing to win 1,000,000 AAdvantage miles!"

The link to this promotion can be found at AA.com, AAdvantage, newsletters.