Knuth gives higher rewards for works he believes have fewer errors. For TeX and METAFONT, he started with 1 cent for every bug found, and doubled it each year u

Knuth gives higher rewards for works he believes have fewer errors. For TeX and METAFONT, he started with 1 cent for every bug found, and doubled it each year until reaching the current value of 327.68 dollars (= 0x$80.00): for example Eberhard Mattes and Oleg Bulatov (joint 7th on the list) have all their amount from a single (and the latest so far) bug found in TeX and METAFONT each (if you're wondering what the bugs were: https://tex.stackexchange.com/questions/154873/ https://tex.stackexchange.com/questions/154873/ — the TeX bug was a missing space in the debug output for a macro with an empty name). Incidentally, he seems to have had this policy of giving out rewards for errors from the time he was a college student: http://ed-thelen.org/comp-hist/B5000-AlgolRWaychoff.html#7 http://ed-thelen.org/comp-hist/B5000-AlgolRWaychoff.html#7