How many occurences of a date, since start date

I can't seem to wrap my head around this right now.

The situation: Need to calculate how many 26ths of a month have transpired since November 1, 2011.

As elementary as this sounds, I've spent an hour on this and have had to rewrite it over and over.

Someone please bail me out. A hint? Anything, please.

Thanks.

Every month has a 26th so count the number of months between then and now, and +1 if today is on or after the 26th.

Now (2012*11=22132) - then (2011*11=22121) = 12. Today is the 16th so don't add one. Thus your answer is 12.

Thanks.