What is the present value of these payments? It depends on the opportunity cost of capital,which in this case equals the rate of return offered by other government debt issues denominated in euros. In October 2011, other medium-term French government bonds offered a return of about 2.4%. That is what you were giving up when you bought the 5.0% OATs.
Therefore, to value the 5.0% OATs, you must discount the cash flows at 2.4%: