You'll never get the correct answer without the correct conversion factor. Note carefully that you have no decimal. It should be
1 km = 0.6214 miles
1000 m = 1 km
60 seconds = 1 minute
60 minutes = 1 hour.
2.998E8 m/s x (1 km/1000m) x (0.6214 miles/km) x (60 sec/min) x (60 min/hr) = ?
