I'm a 68 year old retiree and a basic user of Excel. I can do various
simple tasks, but arrays and complex formulae allude me. Also I don't
know the various names of functions, so I can't use the Help to look up
what I want. This looks like it could be a very simple formula or array
function if I knew the functions or symbols to use.

This is just for a home budget spreadsheet, so no one's fortunes are in
jeopardy. :-)

Let's say I have a number of rows with a math function of A1 + B1 = C1,
A2 + B2 = C2, etc.

I would have to make a separate 'C' column function for each line, like
=A1+B1
=A2+B2

If I had 25 lines, I would have to make 25 separate formulae for each line.

How can I use one identical line function formula for each line in the C
column?
Such as, =A(code for same line number)+ B(code for same line number),
which should give me the result of the particular line in the C column.
This should allow me to Cut and Paste the same formula in each C column,
as lines are added.

Thanks