Rambam in his Introduction to his Commentary on the Mishna writes:
"...And when the one prophesying is fit for prophecy, according to that which is appropriate, we say to him, "Prove [yourself] to us with predictions and tell us things from among that which the Holy One, blessed be He, has taught you." And he tells and promises [their truth]. And if all of his predictions are substantiated, then we know that all of his prophecies are true. But if he lies about it, or even if one of his words fails – and even if it is a small thing – we know that he is a false prophet...And we should not believe him and say that his prophecy is true when one or two of his proofs are realized, but [rather] his [status] should be contingent until his true signs be many – 'like all that he spoke in the name of the Lord' – one time after another..."
And in Hilchot Yesodei Hatorah 10:1-2, 5 writes:
"...But it shall be said unto him: "If thou be a prophet, fortell things which are to come to pass". If he, indeed, foretells, we wait to see whether his words will come to pass or whether they will not come to pass, when, if even a minute detail be wanting it is certain that he is a false prophet. But if all of his words come to pass, he must be in our eyes trustworthy. The examination must be continued many times; if all of his words be found true, lo, this is a true prophet...A prophet whose prophecy had already been proclaimed, and whose words were believed time after time, or if another prophet gave testimony concerning him, and he continued to follow the paths of prophecy, must not be looked upon with suspicious thoughts, or question the truth of his prophecy. And it is forbidden to test him more than necessary, or go on testing him forever..."
My question therefore is, how many times must an aspiring prophet be tested? Is there a set numerical minimum of tests that must be completed? The Rambam writes "many", but what does that mean?