I think Carol Vordamen has a book out which aims to train your brain into remembering maths calculations etc.
http://www.amazon.co.uk/Super-Brain-Easy-Ways-Agile/dp/0091917026/sr=8-1/qid=1171458967/ref=pd_ka_1/202-8062630-4517461?ie=UTF8&s=booksAlso, she was on BBC Radio 2 promoting another book for training your brain for numbers calculations etc, Type "carol vorderman train your brain" into Google, you can see the top link. (sorry link blocked at work!)