According to the problem, we have to convert 4012 mm into km.
We know that there are 1000 mm in 1 m, and also there are 1000 m in 1 km. So we can do a two steps conversion to get the answer in km. So:
1000 mm = 1 m
1000 m = 1 km
Distance = 4012 mm * 1 m/1000mm = 4.012 m
Distance = 4.012 m * 1 km/1000m = 0.004012 km
Distance = 0.004012 km
The distance in km is 0.004012 km