Answer:
Our conversion factor is: 1km = 1000m; 1000m is 10^3m. Since there are more meters in kilometers, we can't divide but multiply. We have 6km times the amount of meters in 1km = 1000m or 10^3m. That is why 6*10^3 = 6000m which is 6km in meters.
Another way of looking at this is;
[tex]6km(\frac{1000m}{1km})[/tex] There's 1000m in 1km (so we use it as a conversion factor). We multiply 6 * 1000 and divide by 1.