Kilograms (kg) is a unit of mass, while millimeters (mm) are a unit of distance. Thus, you cannot compare the two.
2,000,000 milligrams = 2 kilograms
1000 mm equals one meter
6.3 centimeters equals 63 mm.
1.5 cm equals 15 mm.
1 km equals 100,000 mm
15 mm
6,800 mm
63 mm
84 mm ;-)
457.2 mm.
It equals 35 mm.
About 66 mm (65.99).