I need to find out for how many months each person in my database has been making payments to their retirement account. This would be realtively easy, except for the provision that if they contributed any amount during a month, it counts as a contribution. if they contributed for only one week (or one day) of a month, or if they contributed for thirty-one days, it counts as one month's contribution.

I can copy and paste a column containing each week in which the people have been making contributions into Excel. it might look like:

12/12/1998
12/5/1998
11/28/1998
11/21/1998
11/14/1998
11/7/1998
10/31/1998
10/24/1998

This would count as three months' contributions. Unfortunately this is the only data I have on their contributions.

Of course most of the columns are much longer (up to 500 entries long). I'd like to create a formula, or some other kind of operation, that would count the months listed.

I'd also like to know (just for my own knowledge) how I could count the number of weeks in this same problem. obviously you could subtract the top row number from the bottom row number and enter it manually but it would be nice if this could be done automatically as soon as you copy and paste the column into the worksheet.

Any suggestions about how to do this problem are appreciated.