Yeah. “Calories in calories out” is correct in theory but it is an oversimplification. Most people burn a vastly majority of their calories “at rest” by just maintaining their body temperature.

Just to add to this. Another way could be to find a specific construction. If you could for example find an algorithm that given any even integer returns two primes that add up to it and you showed this algorithm always works. Then that would be a proof of the Goldbach conjecture.

Linux Mint is pretty good, it has a Windows 7 kind of feel to it. Fedora is also nice, it great for tablet, also with touch. Both work pretty well and consistently out of the box.