Two possible solutions.

1 - VBA without a formula in the cell. You can use the on change event to
catch changes to one cell and then calculate the required value and put it in
the other cell. Fairly straight forward to do but we will need a bit more
info to hel you.

2 - A bit of slight of hand using the Camera. Check out this link. (you will
also need to use data validation to ensure only one cell is populated at any
given time)
http://j-walk.com/ss/excel/odd/odd04.htm
--
HTH...

Jim Thomlinson


"New user" wrote:

I would like to be able to input a number into Cell 1 and obtain a
calculation in Cell 2 via a formula and equally input a number into Cell 2
and obtain the reciprocal in Cell 1 via the same formula whilst guarding the
formula.

Very many thanks in advance