summate vs sum up

summate and sum up both are verbs.

Word	Noun	Adjective	Verb	Adverb
summate	No	No	Yes	No
sum up	No	No	Yes	No

As verbs, summate and sum up are synonyms defined as:

Other synonyms of summate include add, add together, add up, sum, tally, tot, tot up, total, tote up.

summate (verb)	sum up (verb)
determine the sum of	give a summary (of)
form or constitute a cumulative effect	determine the sum of
	be a summary of