result formule

Hey everybody, I'm new here, hope that i enter my qeustion at the write place

I want to see the result of a formule in a other cel
For example cel A3 contains the formule =a1+a2 , fine, but I want to see the result of it in cel B3
This cel B3 may not have any kind of formule, this cel would be used as a guideline for the user and would be overwrite by the user.

hope this is possible, it is quite important to me

In B3 you could write =A3

Maybe simple
Then I should show the result in a protected cel and let the user decide to use the result and write it in the empty cel.
It's an idea but not exactly the way I want it to be