From Invoice Date - get No of days

Hi,

I have invoice date,

in my report there is calculations need tobe done for the following.

Case - MTD

Invoice Date - 2009.03.24. I need to capture no. of days in that month ie, 03 (march)

Case - Elapse Days

no of elapse days since 1st of every month ie, if current day is 2009.03.24, elapse days will be 24days....not the working days...but all the days in that month from 1st of ebery month to till today.

provide your suggestions.

pratap