1 Mm = 1,000,000 m
and
1,000 m = 1 km
we need to convert 1,000,000 meters to kilometers using the conversion 1 m = 1,000 km.
[tex]\sf{1,000,000~m \times \frac{1~km}{1,000~m}= 1,000 \times1~ km = \boxed{\bf{1,000~km}}[/tex]
So:
1 megameter = 1,000 km.