Anyway you must at least assume that your brain is able to remember that you wrote down the passwords on the pad of paper, and where the pad was stored, without forgetting that this brain is going to use a computer.
So a minimally functioning brain can be assumed.
Now what is required to the brain is not much more elaborated than that.
From the list of partial passwords, say written on paper, but not necessarily, you modify the partial passwords with a simple rule, like:
- adding your pet name to the written down partial passwords (not very good actually), better
- replacing the last 3 characters with the next ones in the alphabet, or
- swapping the odd and even positioned characters,
Something sufficiently simple but personal your brain will keep with quasi certainty. Something also that doesn't reveal some obvious structure in the password in case someone has access to a full password (thus the pet name addition is not very good on this regard).