Answer:
A kilometer is 10⁶ times as large as a millimeter.
Step-by-step explanation:
In the metric system first we have: millimeter, centimeter, decimeter and meter. Each one of these is 10 times the other (1 centimeter is 10 millimeter, 1 decimeter is 10 centimeter, 1 meter is 10 decimeter). Therefore, 1 meter is 10x10x10 millimeter = 1 meter is 1000 millimeters.
But we know that 1 km is 1000 meters,
Therefore, 1 km = 1000 meter = 1, 000,000 milimeter = 10⁶ milimeter
So then, we have that 1 kilometer is 10⁶ as large as a milimeter.