How do I have one column be the sum of two other column automatically and infintitely

Question

I have two columns A and B, and a third column C. I want row N in column C to automatically sum and values in row N of column A and B.

I want to summing to occur from the second row onwards, infinitely.

Is this possible to do?

Answer 1

Delete everything (including any header) from C1.

Then place this in C1:

=ArrayFormula({"Header";IF(A2:A&B2:B="",,A2:A+B2:B)})

Just change Header in the formula to whatever you really want the header text to be.

If the formula does not work, you may live in a locale that uses semicolons where the US uses commas. In that case:

=ArrayFormula({"Header";IF(A2:A&B2:B="";;A2:A+B2:B)})