(Corrects to remove reference to biggest ADP increase in a year)
NEW YORK, March 6 (Reuters) - U.S. stock index futures extended gains after data showed private employers added 198,000 jobs in February, topping analyst expectations, while January's data was revised higher.
S&P 500 futures rose 6.6 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration of the contract. Dow Jones Industrial Average futures added 57 points and Nasdaq 100 futures climbed 6.25 points. (Reporting by Chuck Mikolajczak; Editing by Grant McCool)