That's been one strategy I've seen mentioned in regards to Shor's algorithm many times. Since there's the probability of an error, you still have to check it a

That's been one strategy I've seen mentioned in regards to Shor's algorithm many times. Since there's the probability of an error, you still have to check it and rerun it a few times until you confirm the right answer. That's still many times faster than you'd get conventionally, so it's a reasonable trade off. But it doesn't address the possibility that you can't entangle enough qubits to begin with, or keep them stable long enough to actually perform the calculations, which is where the error correction stuff comes in. I don't know enough about the challenges there to comment on how many you'd need (though 1000:1 seems high to my naive intuition, i'd guess maybe 10-100 for magnitude myself).