Setting up an accumulator in this way is not advisable:
- How do you correct it if there was an erroneous entry in A1?
- You would have no history from which to verify a particular value in A2.

If you are determined to proceed anyway, there are two possible approaches:
- create a circular reference with calculation options set to a maximum of
1 iteration
- write a macro tied to the worksheet change event to do the accumulation

http://www.mcgimpsey.com/excel/accumulator.html
gives details

Jerry

"tfrazier" wrote:

Is it possible to have a cell keep accumulating value from a value entered in
one cell. For instance if cell A2 has 10 and I enter 10 in A1, I would like
cell A2 to increase to 20.