None.
A millimetre is a measure of length in 1-dimensional space while a square kilometre is a measure of area in 2-dimensional space. The two measure different things and, according to basic principles of dimensional analysis, any attempt at conversion from one to the other is fundamentally flawed.
There are 250,000 mm in 0.25 km.
1 km = 1,000 m = 100,000 cm = 1,000,000 mm1 km^2 = 1,000,000,000,000 mm^2 or 10 ^12 mm^210.8 km^2 = 10.8 x 10 ^12 = 1.08 x 10^13 mm^2(10,800,000,000,000 mm^2)
1 mm= 1/1000 km
10000 mm = 0.01 km
4.3 mm is equal to 0.0000043 km
8490 mm = 0.00849 km
25.6 kilometers (mm / 1,000,000 = km)
To convert from mm to km, divide by a million.
There are 6,000,000 mm in 6 km.
1,000,000 mm = 1 km
1000 mm = 1 m = 0.001 km
6,000,000 mm