Christians and Numerology | Numerology Compatibility

Let's take the Harold Camping awkwardness in a slightly different direction.
One common thing I've seen with every end-of-the-world prediction I've ever seen, is this obsession with the numbers of the Bible. 

'He says certain numbers repeat in the Biblealong with particular themes. The number five means "atonement;" ten equals "completeness;" 17 is "heaven." Multiply those numbers by each other and multiply the result by itself. It equals 722,500."Christ hung on the cross April 1, 33 A.D.," he says. "Now go to April 1 of 2011 A.D., and that's 1,978 years."If you multiply that number by 365.2422 -- the number of days in the solar calendar -- it equals 722,449. And if you add 51 (the number of days between April 1 and May 21) to that number, it equals 722,500. It gets more confusing.'Why are we multiplying those numbers by each other?
Here's another example:
Why would the 120 years of Genesis 6 be "Jubilee Years" when the Jubilee hadn't been instituted yet by Noah's day?  Things get so wibbly-wobbly when we start messing around with, "Oh, that verse doesn't really mean a year, it means a JUBILEE year, so fifty years... and a thousand years is like a day to the Lord, so then we have to take the number and multiply it by a thousand..."  It seems so arbitrary--how do we know which "years" are actual years, which "years" are jubilee years, which "years" are prophetic years, and which "years" are prophetic jubilee years (50,000?).
Maybe this is part of my general dislike of math in general, as a writer, but is numerology really something that should be a part of Christianity?  I'm not talking simply about certain numbers being symbolic--six the symbol of man, seven the number of completion, twelve the number of the tribes and of the disciples, forty the number of the desert, etc.  Sure, there are many numbers with some sort of significance: the three of the Trinity, the seven days of Creation, the fifty years of Jubilee, etc.  Even St. John the Divine kind of hints at this sort of thing when he mentions the infamous "Number of the Beast."  ("This calls for wisdom: let the one who has understanding calculate the number of the beast, for it is the number of a man, and his number is 666.")
But more than that--what about the idea that we can derive more complex meanings than that from numbers, particularly about the future?  There's a difference between saying, "Oh, this number adds this added shade of meaning to this verse," and saying "This number is part of a secret code which reveals hidden meanings in this verse."  While "sacred numbers" are a historical concept in Christianity, numerology was listed as a form of divination (and therefore forbidden) as early as 325 A.D.
And yet so many of the prophetic writings, particularly in Daniel and in Revelation, seem to encourage playing with numbers in that manner.  There seems to be a tension here.