“a hundred days of sermonizing, one fart” → a metaphor for how something that one has put great effort into can come to nothing after even a slight mistake, much as a hundred days of serious spiritual study can be lost to the winds

six

six / the sixth hole of a wind instrument

hundred / a very many, lots, a lot / one hundred years old, advanced age

(obsolete) hundred / (obsolete) a very many

(archaic) hundred / (archaic) a very many

hundred

four, 4

four, 4

the fourth