I just do not understand the way system work. Because I have 90 posts but update only to 56 activities.
So I think it a certain number each time update. Like 42 will go to 56 and then go to xx ... Is that how it works? I am just curious.
You can earn a maximum of 14 activity in a 2 week period.
Activity is determined as min(time * 14, posts)
time = number of two week periods you've posted in since registering.
The start dates two week periods are as listed here -
https://bitcointalk.org/index.php?topic=582736.0