There are various ways to copy a formula. One suggested method is:
Select the cell containing the formula.
Choose Edit - Copy, or press Ctrl+C to copy it.
Select the cell into which you want the formula to be copied.
Choose Edit - Paste, or press Ctrl +V. The formula will be positioned in the new cell.
If you want to copy a formula into multiple cells, there is a quick and easy way to copy into adjacent cell areas:
Select the cell containing the formula.
Position the mouse on the bottom right of the highlighted border of the cell, and continue holding down the mouse button until the pointer changes to a cross-hair symbol.
With the mouse button pressed, drag it down or to the right over all the cells into which you want to copy the formula.
When you release the mouse button, the formula will be copied into the cells and automatically adjusted.
If you do not want values to be automatically adjusted, then hold down the Ctrl key when dragging. Formulae, however, are always adjusted accordingly.