Regifting Robin
http://www.regiftable.com/regiftingrobinpopup.html
The Trick Revealed
All 2-digit numbers from 10 to 99, after computation, result in one of the numbers 9, 18, 27, 36, 45, 54, 63, 72, 81. Each of those 9 boxes in the table contains the same gift item (randomly chosen to be different each time you play).
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