Five hundred atmospheres is a lot before it becomes a real gas. If it exceeds 10 atms, you are dealing under real gas standards. As user djones explained, under ideal conditions, the gas molecules are so spanned out from each other that volume can be negligible. Try picturing this instead of memorizing. Now take a piston and press down. The space of the gas molecules are closer together. That decrease in space, makes the gas molecules "count" and "noticeable". Before it was "Oh, that gas molecule over there, yes... that's it, that one! Oh don't worry about that small thing over there, look at all this space we have. So the tenet and the landowner signed on the lease that "gas molecules" were going to be negligible. Ten years went by (10 atms) and the tenet and land owner redrafted the lease because housing sizes were cut in half due to a decrease in space (there was an influx of population coming in). Now, this space is pretty valuable and those gas molecules are no longer negligible, they need to be "counted" in the lease. We have a reduction in space.
Don't worry about memorizing if it's low or high temp. Just know that you have lots of "land" or volume and if you know that PV=nRT, there is a linear relationship, high V, high T. In opposite manner, high V, low P.
This is a concept that is frequently tested. Please make sure you have covered all your tracks in this section. For clarity, when I mention that the gas molecules are no longer counted as negligible, that means they now have volume (>10 atm). On the MCAT, they will usually not place it at such a border line, but will give you enough signs that it is a real gas.
Best Regards.