1) Yeah the English were stupid as well, but at least they realised and have moved onto the metric system. America is now the only country holding us back, refusing to move to the metric system for god only knows what reason (presumably because it was invented by the French. Maybe they should call it the "freedom measurement system"). So I still feel justified in saying "Stupid Americans".

2) Yes I am aware feet are a real measurement system, but they, as well as other imperial measurements, shouldn't be used in physics calculations. At first glance, I actually thought he plugged the feet into the formula, but it appears that Google Calculator is smarter than me and worked it out properly for him. So perhaps he's not as stupid as I first thought, thanks to the might of Google Calculator. 

His math is wrong. If he is using m/s for gravity then he needs to use meters for the radius aswell, otherwise the system falls apart. He really should be using SI units for everything.

Also, I wonder what he put in for Mario's mass?

Google calculator performs any necessary unit conversions.  Try it out sometime, it's awesome when you put in a calculation in 17 different units and it just spits out the answer you want.

BTW, there are good reasons for using the imperial system instead of metric.

Actually, I find it kinda amusing. Everyone my age that I've talked to about it in America had to learn and begin using metric measurements in middle school science courses, so at least the younger generation should at least have some understanding of the measurements. At least for distance and maybe volume and mass. I still have some trouble converting temperature.