Really? How would YOU propose the TEST it?
Let's see now I could add "1" to every number betwenn 0 and 10 billion and when I'm done I'll try adding 2, then 3 and so on untill I've done a billion plus a billion. Then maybe I try negative numbers then move on to division and square roots. If I do 10,000 tests per second could I actually finish before the sun runs out of hydrogen fuel to burn. Gosh no.
So it seems testing is not the way to go here.
How about spot checking? Here is a good example -- I have a new theorem: "60 is divisable by all integers?" Let's try: 1 goes into 60?, Yes., 2, yes, 3, yes, 4, yes, 5, yes, 6, yes. this is to slow, 10, yes, 20, yes , 30 yes. end of proof: "60 is divisable by all integers.
OK so much for spot checking.....
So if it's "easy" tell us how you whould do it and if your method would find the problem where the square root of pi/0.334 is wrong in the 6th decimal place.
Actually checking a calculator is used as a classic example of a hard problem. How to find that one in a trillion error in the 6th decimal place and you can't exaustive test and you can't spot check. You are prettymuch stuck with a functional analysis of the design and what they call "white box" testing.