To accomplish this, you can use a mixed cell reference for the denominator ($C$2) in your formula. A mixed cell reference is a combination of an absolute cell reference (using the $ symbol) and a relative cell reference (without the $ symbol).

Here's how you can modify your formula in cell B10 to use a mixed cell reference:

1. Select cell B10.
2. Edit the formula in the formula bar to change it to =
   Code:

   C10/$C$2

   .
3. Press Enter to confirm the formula.

The $ symbol before the C and the 2 in $C$2 makes them absolute cell references, which means they won't change when you copy the formula to other cells.

1. Copy cell B10 by selecting it and pressing Ctrl+C.
2. Select the range of cells where you want to paste the formula (B13:B22 in this case).
3. Right-click on the selection and choose "Paste Special" from the context menu.
4. In the "Paste Special" dialog box, choose "Formulas" and click OK.

The formula in each cell will now reference the corresponding cell in column C and the absolute cell reference $C$2 for the denominator.

Alternatively, you can also use the "Fill Handle" to copy the formula down to other cells:

1. Select cell B10.
2. Hover your mouse over the bottom-right corner of the cell until it turns into a black cross.
3. Click and drag the cross down to the last cell where you want to copy the formula (B22 in this case).
4. Release the mouse button to copy the formula to the selected cells.

The formula in each cell will now reference the corresponding cell in column C and the absolute cell reference $C$2 for the denominator.