I was curious as to how the cash prizes [1] for this challenge compared to playing the lottery. Consider the next smallest one left: RSA-768. By my very rough estimates [2], $1 worth of computing time on a typical desktop gives you a probability of 10^-58 of factoring the prime by picking random numbers smaller than its square root.
[1] https://en.wikipedia.org/wiki/RSA_Factoring_Challenge [2] https://www.google.com/#q=%241+%2F+(%240.09+%2F+kwh)+%2F+100...