tot vs add up

tot is a noun but add up is not a noun.

Word	Noun	Adjective	Verb	Adverb
tot	Yes	No	Yes	No
add up	No	No	Yes	No

As verbs, tot and add up are synonyms defined as:

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

tot (noun)	add up (noun)
a young child who is just beginning to walk
a small amount (especially of a drink)

tot (verb)	add up (verb)
determine the sum of	determine the sum of
	be reasonable or logical or comprehensible
	to measure up to in kind or quality
	add up in number or quantity