If "multiples" is to "product", "_____" is to "sum" I know this might be a really simple question for those fluent in English, but I can't find the term that describes numbers that make up a sum. 
The numbers of a certain product are called "multiples" of that "product". 
Then what are the numbers of a certain sum called?

"Summands" 
$\phantom{\text{(hmm, first time MSE says my answer is too short; P.S., added by mixedmath: either this or adding empty sets is a good way to add to the length ;p)}}$
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