There are 1000 meters in 1 kilometer. So divide 2564 by 1000 to get the number of km. To divide by 1000, just move the decimal 3 places to the right...
2564 / 1000 = 2.564 km

AlphaWiersteiner

1000 meters is equal to 1 kilometer.
Then the answer is
2564= 2.564