dayOfMonth(<Date>) : Number
The dayOfMonth function is used to extract the calendar day of the month from the specified date parameter.
When you use static dates, you need to enclose the value with the # symbol. The date should be in the following format - dd/mm/yyyy hh:mm
dayOfMonth(#15/02/2021 12:00#) => 15
Learn more about how you can get started using the Formula Field.
Type above and the results will be displayed here.