use this.
=DayNumberOfMonth(LastDayOfMonth(ToDate(userresponse("Enter date");"dd/MM/yyyy")))
According to prompt date format change the date format in the formula.
use this.
=DayNumberOfMonth(LastDayOfMonth(ToDate(userresponse("Enter date");"dd/MM/yyyy")))
According to prompt date format change the date format in the formula.