That very much depends on the size of the solution space. If they get one bit of 'answer' from each qubit used in the computation that's 2^81 possible solutions, in which case you'd expect random chance to require somewhere around 1,000,000,000,000,000,000,000,000 trial runs before they happened to get one right.

Now, I highly doubt the solution space is anywhere near that large. But without knowing more about it we cannot infer anything from the 13/10000 statistic presented.