add up
[verb]
Synonyms: count up, add, compute, count, reckon, total, tot up

[TahlilGaran] English Synonym Dictionary ▲

add up phrasal verb (see also add)

1. to calculate the total of several numbers:
I can add up in my head quite easily.
add something ↔ up
Specialized software adds up the statistics.

2. not add up
a) if a set of facts does not add up, it does not provide a reasonable explanation for a situation:
He was troubled by a feeling that things just didn’t add up.
b) if sums, numbers etc do not add up, there is a mistake in them:
These figures don’t add up.

3. it all adds up informal used to say that lots of small amounts gradually make a large total:
There are five of us using the phone so it all adds up.

[TahlilGaran] Dictionary of Contemporary English ▲

add up
1.
to be reasonable.
His story of what happened to him just doesn't add up.

Usage notes: usually used with not, as in the example
2.
to increase in expense.
With five kids in the family, our medical bills really add up.

[TahlilGaran] English Idioms Dictionary ▲

add up
1. • add up
to total up to a certain amount
I began to add up the money that I owed my father.

2. • add up (to something)
to mean something, to result in something
The things that he said about his boss do not add up.

[TahlilGaran] English Idioms Dictionary ▲

add up
v.
1. To come to the correct amount.
The numbers wouldn't add up.
2. informal To make sense; be understandable.
His story didn't add up.

[TahlilGaran] English Idioms Dictionary ▲