its a very simple method, in childhood if you are an Indian every school insists on bharakhadi that is for eg., k. kha. g. gh. etc., so if you repeatedly chant the varnamala completely you send sound waves to you body which is a medicine to energise and increase your memory power it oils the memory and rejuvenates the brain cell. That is why in our school primary days this pattern was set in schools so as to develop and nourish the little brains
To improve memory ,first eliminate all unwanted negative memories,thoughts,feelings and fear.And then take practice meditation.After relax go for your memory matters.
You can do so by trying to do calculations in ur mind and not on a paper or calculator, this will help u improve ur memory power.
You can do this also by reading and remembering more words while u r copying some thing.
You can improve n grow ur brain by raising ur concentration power which can be done by staring a thing for a short time (like few minutes)
or by chanting God's name.
Best of Luck!
One can improve brainpower by knowing its physical property and function.Then freeing it from myriads of outer distractions/illusions and tasking it with a single task.Also feeding it with regular dose of breath control also helps.
If the reason you ask is to help you remember something boring like the multiplication tables or important phone numbers then repetition, repetition.
Our brains will function best when we see or learn interesting stuff.
I know because my nephew suffers from ADD but only if he is bored. His best subject is chemistry and he never has a problem remembering the names and composition of elements.
To help the brain along you could take some gincko biloba capsules, or what I find very effective, Dr Bach's flower essences or Australian Bush Flower essences.
It goes without saying that tobacco, alcohol and drugs do no favours to our brains.
There is a game called MIND TRAP by playing this game, it is said that it stimulates certain parts of the brain that help with memory and critical thinking!!!