If you are doing a currency conversion, then you may well have to change it
again. By converting the data absolutely you will lose any history as the
underlying data is actually changed, which may or may not be what you want.
If however, you would rather be able to put your conversion factor in a single
cell, and then have all your data drive off that single cell, try this:-
Assuming cell A1 is empty, put 1.87 in cell A1
In cell B1 or any other empty cell, put =$A$1
Now copy that cell with the formula in it, select all your data that you wish to
convert and do Edit / Paste Special / Multiply. They will now all still contain
the original data, BUT, will also contain a formula that multiplies them by what
is in cell A1, and will look as follows
Before
23
14
17
etc
After
=23*($A$1)
=14*($A$1)
=17*($A$1)
You can now change this value in A1 at will, and all your data will change
accordingly.