How to subtract from row above and output to a different column for all rows?

[Drfox]

so I want to subtract from row above and output to a different column for all rows. for instance

1

3 2

4 1

8 4

But I want to do this for all rows in the A column. and output into the C Column Any help is appreciated.

[mikekaganski]

In B2:

=A2-A1

and drag-copy down.

[Drfox]

Thank you very much this worked well