The following formula will put 123 in front of the number in A2. Copy down
with the Fill Handle.
=VALUE(123 & A2)
For a permanent change, copy this column, then over the original column, do
Edit - Paste special - Values. Now you don't need the formula column any
more.
It could be as simple as say, using putting 1000 in a cell, then copying it
and doing a paste special > add if you want to bump up an entire col of
small numbers by 1000, or it could be something else? which may not be as
simple
For more pointed suggestions, post some sample data (in plain text) of what
you have and what you want done, expected results, etc ..
You could give the cells a custom number format of:
"na"General
and still keep those values numeric.
But this just changes what you see--not the values in the cell.
Or you could use a helper cell:
="na"&a1
and drag down.
(convert to values (edit|copy, edit|paste special|values) if you want--and
delete the original range.)