The sum of 2 + 2 is 4.
Your sum is incorrect. Let me sum up.
I keeping getting the wrong sum! The correct sum is what I am seeking.
I gave you a sentence with the word nutrient in it.
I am trying to find the sum of some numbers.
The word him is the pronoun in the sentence.
The word 'in' would be a preposition in the example sentence you gave.
I gave my teacher the homework that is due today.
I'm sure that you will see that the sum of our experience, more than justifies our fee.
The answer I gave was wrong.
she gave him a demure smile
He gave with great piety.
The words to sum up, are used to conclude or summarize something. An example used in a sentence would be "Mike decided to sum up the events in a small article."