We have good information about the abilities of quantum computers with this kind of problem. We have a proof of the best speedups possible, and we have an algorithm which gives that much speedup.
Generally, the answer is that the quantum computer takes the square root of the number of operations taken by the classical computer.
This is far too many to be practical. The number of subatomic particles in the entire universe is something like 2 to the 300th. If each one of these was somehow able to function as a separate quantum computer, your problem would still require 2 to the 499,999,700 power calculations.
Hal