I did but comparing my code with that of others it seems I used a very different solution method to most people. I took my cue from the merge algorithm outlined on the Wikipedia page about Hamming (aka regular) numbers.

I got stuck with this problem too. I was using "hash.delete_if" – when I switched to the non-destructive "hash.reject" it worked fine.

It might be worth adding a line to the kata description warning people that the input hash should not be messed with.