For the number bit ~
Post box number TRA BCDD
E = B + D
Maths bit - N50 (ExB)+D.D-B B E-A W005 C E+A.A B E+B
Please replace covered, thank you.
The Fine Pair series was originally started by wizardsmum.
If anybody would like to place 'A Fine Pair' of their own please do, I would just ask that you let mattd2kat email@example.com know first so he can keep track of the numbers and locations to avoid duplication.
He also keeps a public Bookmark List of this series so once your cache is published please contact him via his profile page to have yours added.