How can I check in Rules if the number of members is below 50 or not? I need to add some user points to users when they signup to the site. Using the Rules module I already provided that functionality. But problem is to add some less points after 50 members have signed up.

So how can I implement a condition to differentiate the people that are registered:


first 50 members means Sign-up (first 50 = 20,000).
after 50 members add 3000 points to user signup .


Anyone suggestions?
You need get the count of the total users so far from the users table.
To do that, you can use a condition with php code where you have to write a db_query("SELECT COUNT(*) FROM users"); //[not tested] 

if result gets number of existing users. you can return true/false to go to the action in order to assign points.

Let me know if you got it working.