It would be very tedious to insert $s in every cell. I have found out how to do this for an individual cell, but not how to do it for a range of cells.
The way to do it for an individual cell is:
Click in the formula slot somewhere (which is near top of screen),
then Ctrl+A (highlights the contents, ie makes it dark)
then Ctrl+C (copies what is highlighted)
then Esc (exits the formula slot)
then paste into a selected cell.
This can also be used to paste the formula into a text document. Thanks.