If the average airspeed of an unladen European swallow is 11 ms calculate this in furlongs fortnight?

My pleasure !

(11 meters/second) x (3.28084 feet/meter) x (1 furlong/660 feet) x (86,400 seconds / day) x (14 days/fortnight) =

(11 x 3.28084 x 86,400 x 14) / (660) (meter - foot - furlong - sec - day / sec - meter - foot - day - fortnight) =

66,141.7 furlong/fortnight (rounded)