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Knuth reward check
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<h2 id="history">History</h2> <p>Knuth started rewarding people for discovering errors in his books after he published the first volume of <i><a href="/facts/The_Art_of_Computer_Programming/MR1bMD9e">The Art of Computer Programming</a></i> in 1968.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Initially, Knuth sent real, <a href="/facts/Negotiable_instrument/bvU79Y5c">negotiable</a> checks to recipients. He stopped doing so in October 2008 because of problems with check fraud. As a replacement, he started his own "Bank of San Serriffe", in the fictional nation of <a href="/facts/San_Serriffe/ryuGGgAM">San Serriffe</a>, which keeps an account for everyone who found an error since 2006.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> Knuth now sends out "hexadecimal certificates" instead of negotiable checks. </p><p>As of October 2001<a href="https://en.wikipedia.org/w/index.php?title=Knuth_reward_check&action=edit">[update]</a>, Knuth reported having written more than 2,000 checks, with an average value exceeding $8 per check.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> By March 2005<a href="https://en.wikipedia.org/w/index.php?title=Knuth_reward_check&action=edit">[update]</a>, the total value of the checks signed by Knuth was over $20,000.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> Very few of these checks were actually cashed, even the largest ones. More often they have been framed and kept as "bragging rights".<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p> <blockquote><p>Intelligence: Finding an error in a Knuth text. Stupidity: Cashing that $2.56 check you got.</p>— Seen in a <a href="/facts/Slashdot/vVpMuby2">Slashdot</a> <a href="/facts/Signature_block/9dMP0F36">signature</a>, quoted by Tess O'Connor<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></blockquote> <h2 id="amount">Amount</h2> <p>In the preface of each of his books and on his website,<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> Knuth offers a reward of $2.56 (<a href="/facts/USD/naEEDUhC">USD</a>) to the first person to find each error in his published books, whether it be technical, typographical, or historical. Knuth explains that $2.56, or 256 cents, corresponds to one <a href="/facts/Hexadecimal/02ohQW22">hexadecimal</a> dollar.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> "Valuable suggestions" are worth 32 cents, or 1⁄8 the value of an error (0.2 hexadecimal dollars or 20 hexadecimal cents). In his earlier books a smaller reward was offered. For example, the 2nd edition of <i><a href="/facts/The_Art_of_Computer_Programming/MR1bMD9e">The Art of Computer Programming</a>, Volume 1</i>, offered $2.00. </p><p>The reward for coding errors found in Knuth's <a href="/facts/TeX/HDrl3Yvd">TeX</a> and <a href="/facts/Metafont/j7vCXw8s">Metafont</a> programs (as distinguished from errors in Knuth's books) followed an audacious scheme inspired by the <a href="/facts/Wheat_and_chessboard_problem/TQRz7YdY">wheat and chessboard problem</a>,<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> starting at $2.56, and doubling every year until it reached $327.68.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> Recipients of this "sweepstakes" reward include Chris Thompson (Cambridge) and <a href="/facts/Bogus%25C5%2582aw_L._Jackowski/SR6hhpyN">Bogusław L. Jackowski</a> (Gdańsk),<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> and also Peter Breitenlohner on 20 March 1995.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> </p><p>Each check's memo field identifies the book and page number. 1.23 indicates an error on page 23 of Volume 1. (1.23) indicates a valuable suggestion on that page. The symbol <a href="/facts/Theta/G2ItIJpL">Θ</a> denotes the book <i><a href="/facts/Things_a_Computer_Scientist_Rarely_Talks_About/5oaFjk34">Things a Computer Scientist Rarely Talks About</a></i>, KLR denotes the book <i>Mathematical Writing</i> (by Knuth, Larrabee, and Roberts), GKP and CM denote the book <i><a href="/facts/Concrete_Mathematics/JkEz9aNX">Concrete Mathematics</a></i> (by Graham, Knuth, and Patashnik), f1 denotes fascicle 1, CMT denotes the book <i>Computer Modern Typefaces</i>, DT denotes the book <i>Digital Typography</i>, SN denotes <i>Surreal Numbers</i>, CWEB denotes the book <i>The CWEB System of Structured Documentation</i>, DA denotes the book <i>Selected Papers on Design of Algorithms</i>, FG denotes the book <i>Selected Papers on Fun and Games</i>, and MM denotes the book <i>MMIXware - A RISC Computer for the Third Millennium</i>. </p> <h2 id="delays">Delays</h2> <p>Knuth is often unable to answer immediately when a reader finds a mistake in one of his books or programs. In some cases, the delay has been several years. For example, on 1 July 1996, Knuth sent out more than 250 letters, 125 of which contained checks, for errors reported in <i><a href="/facts/The_Art_of_Computer_Programming/MR1bMD9e">The Art of Computer Programming</a></i> since the summer of 1981. A few of these remain unclaimed as of May 2006.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> When Knuth is not able to reply immediately, he adds 5% interest, <a href="/facts/Compound_interest/e0DKKjBs">compounded continuously</a>, to the reward. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/List_of_computer-related_awards/5Mw77Aul">List of computer-related awards</a></li> <li><a href="/facts/Paul_Erd%25C5%2591s/63LoUTe1">Erdős's problems</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="http://www-cs-faculty.stanford.edu/~knuth/boss.html">The Bank of San Serriffe</a></li> <li><a href="https://www.npr.org/templates/story/story.php?storyId=4532247">Interview</a> (<a href="/facts/RealVideo/XKhRlNfN">RealVideo</a> format) (or <a href="https://web.archive.org/web/20090421090053/http://www.soundbytes.org/phpBB2/viewtopic.php?t=5643">Transcript</a>) with Knuth on <a href="/facts/National_Public_Radio/BohIW9Xg">National Public Radio</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Ditlea, S., "Rewriting the Bible in 0's and 1's Archived 2018-11-09 at the Wayback Machine", MIT Technology Review. <a href="https://www.technologyreview.com/s/400456/rewriting-the-bible-in-0s-and-1s/" target="_blank">https://www.technologyreview.com/s/400456/rewriting-the-bible-in-0s-and-1s/</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Knuth, Donald. "Knuth: The Bank of San Serriffe". Stanford CS Faculty. <a href="https://www-cs-faculty.stanford.edu/~knuth/boss.html" target="_blank">https://www-cs-faculty.stanford.edu/~knuth/boss.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Knuth, Donald. "Knuth: The Bank of San Serriffe". Stanford CS Faculty. <a href="https://www-cs-faculty.stanford.edu/~knuth/boss.html" target="_blank">https://www-cs-faculty.stanford.edu/~knuth/boss.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Donald Knuth (2002), "All questions answered Archived 2019-04-30 at the Wayback Machine", Notices of the AMS 49(3): 318-324. <a href="https://www.ams.org/notices/200203/fea-knuth.pdf" target="_blank">https://www.ams.org/notices/200203/fea-knuth.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>David Kestenbaum, "NPR Interview: Donald Knuth, Founding Artist of Computer Science, at 5:42". NPR.org. 2005-03-14. Archived from the original on 2018-04-03. Retrieved 2018-04-02. <a href="https://www.npr.org/templates/story/story.php?storyId=4532247" target="_blank">https://www.npr.org/templates/story/story.php?storyId=4532247</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Kara Platoni, "Love at First Byte Archived 2006-06-04 at the Wayback Machine", Stanford Magazine, May–June 2006 <a href="http://www.stanfordalumni.org/news/magazine/2006/mayjun/features/knuth.html" target="_blank">http://www.stanfordalumni.org/news/magazine/2006/mayjun/features/knuth.html</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>The History of TeX Archived 2011-08-07 at the Wayback Machine <a href="http://www.tug.org/whatis.html" target="_blank">http://www.tug.org/whatis.html</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"Programming Quotes - stgray.com". www.stgray.com. Archived from the original on 2021-04-17. Retrieved 2021-10-17. <a href="https://www.stgray.com/quotes/programmingquotes.html" target="_blank">https://www.stgray.com/quotes/programmingquotes.html</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>See Books in Print by Donald E. Knuth Archived 2006-09-01 at the Wayback Machine <a href="http://sunburn.stanford.edu/~knuth/books.html" target="_blank">http://sunburn.stanford.edu/~knuth/books.html</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Frequently Asked Questions Archived 2012-02-10 at the Wayback Machine on Don Knuth's webpage . <a href="http://sunburn.stanford.edu/~knuth/faq.html" target="_blank">http://sunburn.stanford.edu/~knuth/faq.html</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Weisstein, Eric W. "Wheat and Chessboard Problem". MathWorld. <a href="/wiki/Eric_W._Weisstein" target="_blank">/wiki/Eric_W._Weisstein</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Donald Knuth (2002), "All questions answered Archived 2019-04-30 at the Wayback Machine", Notices of the AMS 49(3): 318-324. <a href="https://www.ams.org/notices/200203/fea-knuth.pdf" target="_blank">https://www.ams.org/notices/200203/fea-knuth.pdf</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>"Installation of Knuth's 1995 release". Archived from the original on November 20, 2005. <a href="https://web.archive.org/web/20051120141630/http://www.uni-giessen.de/hrz/tex/more_info/info/mailarchiv/mutex.1995/msg00147.html" target="_blank">https://web.archive.org/web/20051120141630/http://www.uni-giessen.de/hrz/tex/more_info/info/mailarchiv/mutex.1995/msg00147.html</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>TUG'95: Questions and Answers with Prof. Donald E. Knuth Archived 2006-11-10 at the Wayback Machine and Ch 34 of Digital Typography <a href="http://www.tug.org/TUGboat/Articles/tb17-1/tb50knut.pdf" target="_blank">http://www.tug.org/TUGboat/Articles/tb17-1/tb50knut.pdf</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>What is your current mailing address? Archived 2018-01-23 at the Wayback Machine on Don Knuth's website. <a href="https://cs.stanford.edu/~knuth/address.html" target="_blank">https://cs.stanford.edu/~knuth/address.html</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> </ol>