Just divide, then multiply by 100...
449 / 578 = 0.77681660899654
0.77681660899654 * 100 = 77.681660899654%
In your worksheet though, you can skip the multiplication by 100 because
Excel allows you to format cells as Percentage meaning the value in the cell
would stay 0.77681660899654 but be displayed as 77.68% (where I am assuming
the number of decimal places is set at 2). So, on your worksheet, you would
have something like this...
=A1/B1
which you could copy down to get the fraction relationship of Column A as
related to Column B. Highlight the "answer" column (the one with your
formula), right-click it and select Format Cells from the popup menu that
appears... select Percentage from the list on the Number tab, set the number
of decimal places and click OK.
Rick