Copy, and paste.
If you want some or all of the cell references to stay unchanged as you
copy, look in help for the difference between relative and absolute
addressing.
--
David Biddulph

MAS wrote:
I want to use a formula for addition and subtraction which will be
repeated on the whole sheet. example C2=C1+A2-A2.This will be
repeated in every cell. How can I do once and don't have to repeat
all the times for whole month.