Working odd summer jobs has been 'the sum of' my experience so far. [=has been all the experience I've had so far]
That picture 'sums' him 'up' perfectly. [=that picture perfectly shows what kind of person he is]
“So, you don't want to go because you think it will be boring?” “That just about 'sums it up'.”
(..) We know your theory, Alexander, but the boy's found a simple geometrical picture. - A tree structure won't work. - Look now. He's joining the two vertices. - But I can do the sum. - Well, it's how you group the terms, Alexander. But, Gerry, if we do the whole thing this way, then... (..)1997 Good Will Hunting