NSY, look closely at the post number in previous pages. It matches the number in the post.
Therefore, 6,447.
EDIT: Hold on. Now that I think about it, they should not match, yet they've been the same for many pages. Either something's wrong or there's a post somewhere without a number.
EDIT 2: It was MagicalToadette's "Hello!" in page 301. UM wanted to count that as a number, but I kept undoing it. I think we should keep counting as we've been doing since that.