How to add a month to an Excel date value? [duplicate]

I tried to google for a while but it seems to have no straight forward way to do this math.

For example, we have the date at B2 12/31/2012 and need to add 2 months to it and store value in B4. What is the direct formula to use? I rather not using any 3rd party addon(s).

http://office.microsoft.com/en-ie/excel-help/add-or-subtract-dates-HP010342155.aspx#BM5

You can use the EDATE function to quickly add or subtract a specific number of whole months to or from a date.

The EDATE function requires two values (also referred to as arguments): the start date and the number of months that you want to add or subtract. To subtract months, enter a negative number as the second argument (for example, =EDATE("2/15/10",-5). This formula results in the date 9/15/09.