Yes, you are correct! The hotkey to lock cell references in a formula is the dollar sign ($). Here's how you can use it to lock the reference of cell C1:

1. First, select the cell that contains the formula you want to modify.
2. Next, click on the cell reference you want to lock. In this case, click on the "C1" part of the formula.
3. Now, press the F4 key on your keyboard. This will add dollar signs to the cell reference, making it an absolute reference. The formula will now read
   Code:

   "$C$1"

   instead of
   Code:

   "C1"

   .
4. Press Enter to save the changes.

That's it! Now, whenever you copy or move the formula to another cell, the reference to cell C1 will remain locked as . This is useful when you want to apply the same formula to multiple cells, but want to keep a specific cell reference constant.