OBTS can mean once bitten twice shy but don't see how the 1 fits in! Aren't they maddening!
I'd say you're right whitevoilet. When these were first posted a couple of days ago, I thought that the number at the beginning had to be part of the answer until:
4: Time as the fourth dimension (Albert Einstein)
so it appears that the number at the beginning is not necessarily part of the actual phrase itself.
You're right, they are maddening!