5 million solid fuel rockets c:
I was thinking, perhaps, nine.

The thing flies beautifully with only one SAS module, but on my previous launch with it it got 7,233m into the air and then began to fall. And if you don't launch it immediately then the eight surrounding engines will fall off the central one.
But hey, I suppose all that matters is that it didn't explode. Although the thrusters did come dangerously close to overheating. Yikes.