If you only knew what I've forgotten

I was thinking the other day about the things I can't remember anymore.

That may sound like a crazy statement but it's not as mad as it sounds. I was trying to do some mathematics the other day and was stuggling. At university my math was good, and the particular problem I was attempting to solve, I knew I used to know how to do it and couldn't remember anymore.

So what's worse, not knowing how to do something. Or knowing that you used to know how do something and have since forgotten?

I think the latter is worse and my current plan is to drink more wine so I forget I ever knew how to do anything.