For the others, such as the estimated amount at the end of month or year, basically, the average per day is multiplied by the number of days from now until the end of the month or year, and then added to the current total. E.g., say there's 4.25 per day, and currently 34 members, and 14 days until December. 14 x 4.25 = 45.5 members (rounded to 46). Add 34, and that means 80 members altogether.