I just noticed that the answer count on user profiles is sometimes different from the number of answers in their "all answers" lists. For example, my profile in RMT says I have 41 answers. When I click "all answers", I get a 3-page list. The first page has 19 answers, the second has 18 answers, and the third has 0 answers. 19 + 18 + 0 != 30. ("!=" means "not equal") So why are the answer counts inconsistent with each other?
If you answered a question which the asker subsequently took down, then it will still contribute to your total answers despite the thread being invisible in activity lists.