If you just want to add 0.27 as a once off to all those cells
You can simply type 0.27 in any cell - select it and choose COPY

Then select C5:C455
Go to EDIT PASTE SPECIAL
From the paste section choose VALUES
From the operation section choose ADD
Then Click the OK button

George


JCE wrote:
for instance in column c from row 5 to row 455 I want to add .27 to every
number that is already in each cell

example c5 has 9.09 already in it, I want to add .27 for a new total of 9.36

I then want to copy that formula so that it does the same thing all the way
to c455