sum of + numbers/items
Expressing a total
Use sum of to talk about a combined total.
The sum of the angles is 180 degrees.
Prepositions used with sum
Different prepositions with sum express totals, results, summaries, or money amounts.
Quick answer
Common combinations with sum
The most common patterns are sum of for totals, sum to for resulting totals, and in sum for a brief conclusion. About sum and with sum are uncommon except in special contexts.
The sum of the numbers is 40.
The expenses sum to more than $500.
In sum, the project succeeded.
The expenses sum to more than $500.
In sum, the project succeeded.
Choose the pattern by meaning
These forms are not interchangeable. Choose the construction by meaning, not by which preposition appears most often.
sum to + amount
Showing a final total
Use sum to with a verb meaning reach a total.
Their costs sum to $2,000 altogether.
in sum
Giving a conclusion
In sum means in short or overall.
In sum, the plan was effective.
a sum for + purpose
Talking about money for something
Use for to explain the purpose of a payment or amount.
They donated a large sum for medical research.
See the difference in context
The same subject can take different constructions because each sentence answers a different question.
Construction
Example
Meaning
sum of
The sum of 8 and 2 is 10.
A mathematical or combined total.
sum to
The figures sum to 100.
Add up to a total.
in sum
In sum, we agree with the proposal.
Overall or in conclusion.
about sum
We spoke about the sum involved.
About introduces the topic, not a fixed phrase with sum.
with sum
They left with a large sum of money.
With expresses accompaniment, not a fixed collocation.
Common mistakes
Some combinations appear in real text but do not mean what learners often assume.
Using sum of after a verb
Use sum to when numbers add up.
✕ The numbers sum of 50. ✓ The numbers sum to 50.Confusing in sum with sum up
In sum is a phrase meaning overall.
✕ In sum the speaker explained the chart. ✓ In sum, the speaker explained the main result clearly.Using about sum as a fixed expression
About normally introduces a topic.
✕ We discussed about sum. ✓ We discussed the sum.Leaving out of after sum
Use of before the items being added.
✕ the sum the payments ✓ the sum of the paymentsQuick practice
Choose the expression that matches the intended meaning.
1. The two invoices ___ $900.
2. ___, the company made a profit.
3. The ___ the values is 75.
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Frequently asked questions
What is the difference between sum of and sum to?
Sum of is a noun phrase for a total. Sum to is a verb phrase meaning add up to.
Is in sum formal?
Yes. It is common in formal writing and presentations.
Can about be used with sum?
Yes, but only when about introduces a topic, as in talk about the sum.
Related preposition guides
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