I have a learning disability of some sort. Looking at Wikipedia it just may be Dyscalculia, the understanding of theory of math but screwing up the processes of it. I find that more often then not when I think of numbers and right them down I'll write down the wrong number(for things like note taking) but I'll remember that the number written down is wrong. It's fun dialing phone numbers when someone tells them to me.
I think a have a speech version of this too. Sometimes I'll think of the perfect word I want to say but I just can't say it, and my brilliant observation is of no help to the listener.