Count number of Mondays in a given date range

Question

Given a date range, I need to know how many Mondays (or Tuesdays, Wednesdays, etc) are in that range.

I am currently working in C#.

Answer 1

Add the smallest possible number to make the first day a Monday. Subtract the smallest possible number to make the last day a Monday. Calculate the difference in days and divide by 7.