Knuth Reward Check

The author recounts receiving a cherished reward letter from Donald Knuth after reporting an error in Computer Modern Typefaces. Knuth’s practice of rewarding any error, even typographical ones, is described as folklore, and the writer explains the unusual mix of disbelief and careful double-checking before reporting the finding. The mistake sits in a conspicuous place: Volume E of Computers & Typesetting, on page Arabic one, in the very first word; the check’s memo therefore reads “E1.” An image of the check is shown but slightly censored because Knuth stopped issuing real checks years ago and worries about misuse of the numbers; the replacement is a fantasy certificate from the Bank of San Serriffe.

The post gives the precise reward notation and a follow-up anecdote: the entry appears as “0x$1.20,” which the author converts to decimal $2.88, and a subsequent, incorrect bug report later earned a small additional check of $0.32 because Knuth counted a throwaway sentence as a worthwhile suggestion and responded with several explanatory paragraphs. The piece stresses the rarity and delight of earning a Knuth check, notes there are no comments on the page, and invites readers to contact the author by email.