I have a simple spreadsheet, one column of which is formatted as numbers. I have entered a sum formula in the usual way. Instead of showing the result the formula appears in the total cell. Why is this happening?

Erroneous space or ,.' maybe. Delete formula and start again. =SUM(A1:A10)

The other thing that can happen is the cell that holds the formula may not be formatted as a number. Check this to be sure and then just like Jackie suggested try writing the formula again.

Checked cells formatted to numbers. Tried deleting column & inserting new. & formatting entire column to numbers.

I know that you can set spreadsheet to display formulae so that they can be checked or copied, e.g. To a Word doc for editing. Could this have accidentally occurred. If so how rectify?

Even though the cells are formatted as numbers have you tried editing the formula or reentering it? Even if a cell is formatted as general if it was formatted as text before it will not take the change until it is edited. Also copy and paste your exact formula in your reply so we can see if there is some kind of character in the text that would cause the issue. Better yet post your book and you will have an answer very quickly.

Thanks