Finding the Last Day of the Previous Month

[BrandonS4]

Hello all!  I am trying to find the correct formula to find the last day of the previous month.  I am running a report that will calculate DSO and I need to multiply by the number of days in the previous month.  Any help would be appreciated!

Thanks!

[KLAMB]

How could this be modified to pull first day of prior month (ie, 2021-07-01).

[BrandonS4]

Previous Month = DateTimeAdd([OriginalDate],-1,"month")

FirstOfPreviousMonth = DateTimeAdd([Previous Month], 1-DateTimeDay([Previous Month]), "days")

LastOfPreviousMonth = DateTimeAdd([OriginalDate], 0-DateTimeDay([OriginalDate]), "days")