>(1) Your formula is not very good. If the day is 31, if won't work

The current value is 01/08/2015. I changed that for 31/08/2015. I did not have any problem.

>(2) that value is 42217. So, directly on that, how can I know what date
>Rightclick cell - format - take Date. That will make it display a date

That works, thanks.

>(3) how can I add directly the number of months on that date
>
>In the same cell ? Say 8 months
>

>=edate(42217, 8)
>

>
>
>In another cell - say 42217 is in cell A2
>

>=edate(A2, 8)
>

Very good, thanks