Wiktionary
n. (context idiomatic English) A concept in holism. Related to the idea that the total effectiveness of a group of things each interacting with one another is different or greater than their effectiveness when acting in isolation from one another.
Usage examples of "sum of its parts".
They swallow each other up, and merge into a single black hole whose event horizon, oddly enough, has a cross section whose area is greater than the sum of its parts.
Smells which mingled to become that special suburban smell which is the sum of its parts.
Andrew Fielding believed something different: that the whole is greater than the sum of its parts.
The thickening mixture of mindwaves was no more than the sum of its parts, and it had stopped trying to be.
Now, stabilizing devices, connectors, and long energy rods held it firm and straight, making the massive vessel less a collection of independent devices than a kind of mechanical organism, a whole greater than the sum of its parts.
The potion took sorcery's spark and became greater than the sum of its parts.
A third and fourth were married together in a union of monstrosities the result of which was more disgusting than the sum of its parts.
It flooded into her, hot with the unique violence of mortal ferocity, and melded with her own elemental strength into something greater than the sum of its parts.
People sitting around the same table were more likely to feel part of the same unit, to be aware of one another, and spark the sorts of ideas and responses that made a command team more than the sum of its parts.