How can I copy a formula multiple times and always refer to the same cell?

"In Excel the $ in front of the Rownumber fixes the row to a constant. A $ in front of the column letter fixes the column.
So you have:

A1 if you copy down, the 1 will change to 2,3, etc; if you copy across, the A will change to B,C, etc
A$1 if you copy down, the 1 stays 1, if you copy across the A changes
$A1 if you copy down the 1 changes, if you copy across the A stays
$A$1 no matter how you copy, its always points to A1"

"OK, I figured it out.

Click the cell you want to refer to repeatedly, then type a name for it into the ""name box"" -- the box that usually displays the coordinates of the selected cell, such as ""A1,"" ""A2,"" etc.

Then once you've defined a name for the cell, use that name in your formula...

=B3-user_defined_name

If you copy and paste that formula it will always refer to the cell named ""user_defined_name."""