- cell C4 is formatted as General
- now in cell C 4 I type:-
=A2+1
- cell C 4 now displays the number 1
- cell A 2 is blank
Now if I type 20 in cell A 2 I get:-
21
- in cell C 4.
As far as I can see I cannot replicate your problem.
Please hit Yes if my comments have helped.
Thanks.