1) How could a probability be greater than 1? (Something you *seem* to claim)
2) Most numbers have small prime factors (in a way that can be made precise in terms of asymptotic densities) so in some sense most numbers have the property that it is relatively easy to find one of their prime factors simply by guessing. For example, guessing 2 nails it 50% of the time. How does that help you factor any specific number, especially one which is the product of two large primes? Answer: it doesn't.
3) If you think that your approach actually has any merit, why not use it to factor one of the RSA challenge numbers? If you think that factors are easy to guess then this should be a pretty easy challenge for you.