At the top of the first page in a newsgroup is the Post Count. That tells you how many posts are in that group.

There are 100 posts per page, and up to 15 pages (1500) posts possible. Not all groups reach 1500.

The post count will change constantly. As each post is added, the number will go up, until it reaches the maximum of 1500 posts.

But, a group may have 1500 posts one day, and 1350 the next. This is normal. Each post in an alt.discuss group has a 30 day life. It will disappear after 30 days.

So, if there are a lot of posts made in one day, when they hit the end of their 30 days they will fall off the board. This will cause the Post Number to change. The posts are dropped 3 times a day.

Another way that posts disappear is when they get pushed off the board. Though each post has a maximum of a 30 day life, some groups are so active that they can post 1500 in a week. When that happens, each new post will push the post with the earliest date and time off the board.

Replying to an old post will not make it stay longer than it's 30 days. At the end of it's "life" it will still disappear, leaving a thread of Re: responses, with no original to refer back to. That is why many people will Cut & Paste the post or the relevant parts of the post into theirs.

If you want to keep a post for longer than 30 days, it must either be re-written or C&P'd into a new post. This must be done every 30 days.