This might help: http://www.bygsoftware.com/Excel/functions/sum.htm

It shows how to sum 40 numbers.

By the way, did you realise that your Caps Lock key was on?

Turn off the Caps Lock and post some detail of what you have now and what you
wish to occur.

If talking about using more than 30 arguments in a formula, there are methods to
overcome that.

One is to use two sets of parens like

=SUM((a1,a2,a3,a9,f5,h7...more than 30 cells))

Show us the formula you are using currently.

Gord Dibben  MS Excel MVP