|re: I need to be able to copy just the $A$1 to the column of cells that already contains a number.|
No, you need to add an = sign, the * operator and the reference to $A$1. You can't do that with a copy/paste or a drag and fill.
The macro I offered will do just what you want - retain the constants in A2 through the last row, while adding the rest of the characters needed to turn the contents of the cell into the formulae you are looking for.
The formula in A2 will end up looking like:
=1293*$A$1 and will display 646.5, formatted however you like.
It would have no impact on A1 - you can change that at any time.
In the future, if you wanted to change the constants in A2 and beyond, you would simply edit the formula in each cell - or reenter all of the constants and run the macro again.
Bottom line is you can't have a constant in a cell and also have a formula. You can have a formula that contains a constant, but it's still a formula.
Why not just hide the column with the constants and use a "regular" formula? That sure would make future editing the constants a whole lot easier.