Synonyms for Add up:

n.

compute, determine, stand to reason, reckon, m reasonable, prove, hold water, assess, project, calculate, estimate. come to, work out, run to, add up to, come out, amount to, make. lie, have a hollow ring, belie, ring hollow. add up (noun)
tally, add, tote up, tot up, make sense, sum up, total, summate, add together, tot, come, sum, number, amount.

v.

stative (verb)
amount, come.

Other synonyms:

assess, come to, estimate, project, determine, add up to, calculate, belie, run to, compute. lie, work out. come out, reckon. make. number
run to.
Other relevant words:
compute, add up to, amount to, determine, calculate, reckon, estimate, work out, come to, run to, prove, assess.