Hi Joel,
First of all, I wouldn’t worry too much about this too much. The bit flipping is just one minor sub-topic of all IPv6 related stuff you can expect in the exam. It’s possible that you don’t get any questions about it so don’t stress about it too much. You can expect a lot of regular subnetting questions so that’s why I highly recommend a “cheat sheet” for that.
It seems this list would work. It might be a quick method if you’d get 10 bit flipping questions but if you only would get 1 question, it might be just as fast to quickly calculate it?
hex > binary > flip 7th bit> hex
So for example:
hex: 12 =binary: 0001 0010
flip 7th bit:
binary: 0001 0000
back to hex:
10
And we are done.