903 B
Proof
TODO
Why do we need mathematical proof if something is obvious? Well, mathematicians need to be most precise and proof enables them to discover absolute truths without any shadow of a doubt (a luxury most other scientists don't have), so they set it as a standard because many things that seem obvious aren't in fact so -- for example numbers 31, 331, 3331, 33331, 333331, 3333331 and 33333331 are all primes so you might think by this pattern also 333333331 will be a prime, but that's not the case because 333333331 = 19607843 * 17. Sometimes patterns deceive us, mathematicians only take proof for the ultimate solution. But indeed e.g. the industry sometimes accepts even unproven but highly likely conjectures to hold, e.g. that P doesn't equal NP, simply for economic reasons (the chance of being wrong is very low and profitability of being right is high).