Well, most calculators find the square root of X as e^(0.5*ln(X)), where e and ln are found using a Taylor series expansion or some other efficient algorithm. Intel processors speed up trig functions by using a look-up table for a close initial guess so the series converges much more rapidly.
I don't know of any processor or compiler that would use a random number generator for a common math functions because random numbers are somewhat expensive to generate (unless done in hardware) and using them would make execution times harder to predict.
The main difference it that humans have to learn to do math, and with computers that is an innate part of their function. If a computer is to think like a human, it needs to be bad in math, as all this mathematical precision is expensive in energy terms. Humans don't usually do e^(0.5*ln(X)) when trying to figure out the square root of some number. One way is to pick a number between 0 and X and multiply that number by itself, if that number is greater than X, then that number is the upper bound of the next number you pick and 0 is the lower bound, otherwise that number picked is the lower bound of the next number picked and X is the upper. If one keeps following that algorithm one gets fairly close to the actual square root fairly quickly. The brain does a lot of its thinking by guesses or random numbers, and often times a quick decision is better than a mathematically precise answer which is what computers are used for.
At this point I have to conclude you know absolutely nothing about actual computer science, so maybe you should refrain from commenting on how to simulate human brains (or anything else, really.)
Actually I have a degree in it, what is lacking is an understanding of how the brain works. Are you saying a future computer can't simulate the human brain? Then you are saying there is a part of the universe that can't be simulated with mathematical algorithms, and that 3 pounds or organic matter in your skull is beyond the ability of any conceivable computer to emulate, the rules at work within the brain are somehow non-mathematical, maybe a soul or spirit separate from the body is involved then?
Its kind of an arrogant position to take assuming the "I'm the expert in computing, and your not, so therefore you must agree with me." So you say you know everything about every possible computer and your telling me that no human brain simulation is possible as what goes on inside the brain is outside the normal scope and rules of the universe and can't be simulated?