adding values from row A to a constant in row B

not sure what you mean by doing 271 rows separately but, here is what I think is the formula you need in cell C2... =A2+B2
then you click out of the cell, then click back in the cell and hover your cursor over the bottom right corner of the cell and the cursor should change to a bold plus sign and the bottom right of the cell will have a small black box in it. Just double click on that and it will auto populate the same formula (changing the rows as it goes down) all the way down until there are no more cells with values in in col B. Hope that helps.

now, going by your post title of adding values in col A to a constant in col B, if you mean you want all the numbers in cells A2 through A271 to have the value in B2 added to them, you would use this instead... =A2+B$2 and populate that the whole way down. The use of dollar signs locks in certain cells, for example $B2 locks in col B but not row 2, so you can drag it to the right and it will always refer to what is in col B. B$2 locks in row 2 so as you drag the formula to the right and down, it will continue to refer to row 2 as you go down but as you go to the right it will change to C$2 then D$2 etc. $B$2 will lock in cell B2 and no matter which direction you drag the formula it will continue to point to cell B2.
Maybe that is what you meant?

then there is one other way I can think of to add (or multiply or divide or subtract) a whole column of numbers by a specific number.
so you put the constant in a cell, say B2, then copy that cell, then highlight the whole column of numbers you want to add it to (or multiply or whatever) and you do a right click and the paste box will open, select paste special and a box will open, then you go to operation and click on Add then OK and what is in cell B2 will be added to the each cell in col A that you highlighted, so if the number in B2 was 2, 2 will then be added to each cell you highlighted in col A. And of course if you don't like the results you can hit undo.

Originally Posted by azpackrat

that formula is =SUM(A+B)

Don't use SUM unless you are providing a list of numbers to add together. That formula, for row 1, is

=A1+B1

Once you put that formula in, you can copy that down the column all the way to row 271. This is the whole power of Excel and a very fundamental feature. If you do that, the formula in row 2 will automatically be

=A2+B2

row 3 will be

=A3+B3

all the way down to

=A271+B271

If you want to use the value in B1 for every row then follow Sam Capricci's second post.

=A1+B$1

Your question can be interpreted two different ways. Please read it over and see if you can clarify this.