I have read that the answer scores are calculated by the formula (Upvotes - Downvotes). I have just done a query using Stack Exchange Data Explorer (SEDE) and see a discrepancy between this formula and the first (most voted, accepted) answer, while all other answers seem to agree with the formula.
See for yourself with the example below. The first answer (most voted, accepted) has a score of 1380, but it should have 1377, since there are 1378 upvotes and 1 downvote, according to the query.
Here is the post I was testing: What are the correct version numbers for C#?
And here is the query I did: http://data.stackexchange.com/stackoverflow/query/425977/answer-up-down-votes-from-a-specific-question