To solve this conversion factor problem we are going to multiply our original quantity 800hm by conversion factors (expressed as fractions) in order to cancel units until we get centimeters:
We know that 1 hectometer= 100 meters, so our first conversion factor expressed as a fraction is

We also now that 1 meter = 100 centimeters, so our second one is

Now that we have our fractions, lets multiply our original quantity by them to get our answer in the required units:

We can conclude that 800hm are
8,000,000cm