He worked on what?
<He Worked>
Two five six three = 2563 = Two thousand five hundred and sixty-three
It was the beating of the old man's heart. It's not madness, says the narrator, "but over-acuteness" of his sense of hearing caused by his nervousness, as he says in the opening paragraph of the story. ... The narrator's obsession shifts from the old man's "Evil Eye" to the old man's loudly beating heart.
