What is the addition formula for Excel spreadsheets?

Simple addition can be done using the + sign:

=A3 + A5

The formula for doing addition in Microsoft Excel can use the SUM function.

=SUM(A3+A15)

You click on the box you want the sum to appear in. In that box you type=SUM( then you write the boxes you want to add up. ex: B1,C1,D1. make sure you put a comma between each box number

ex:=SUM(B1,A1,C1)

To do a block of cells you can use a range reference. To sum all the cells from A2 to A15, you would use a colon in between them:

=SUM(A2:A15)