The reward from DonaldKnuth for the first discovery of a significant error in TheArtOfComputerProgramming.  

Knuth has written many such checks; the vast majority of them have never been cashed.  (Instead, they occupy scrapbooks, and reportedly more than a few have been framed and placed on a wall).

Anyone have a check (from DonaldKnuth) for $2.56?

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To be precise, I think he doubles his reward every time a bug is found in one of his opuses (TAOCP or TeX).  For Tex, I think the "bounty" is up to $10.24.

''So, does that mean if I find 22 more bugs, I'll receive a check from Knuth for $42,949,672.95?  That one I might cash...though I suspect it would bounce - being a college professer doesn't pay ''that'' well...''

Knuth is not just a college professor ...
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I seem to recall that the bounty tops out at 2**15 cents.