"he borrowed a large sum"
"the amount he had in cash was insufficient"
"the sum of all our troubles did not equal the misery they suffered"
"the gist of the prosecutor's argument"
"the heart and soul of the Republican Party"
"the nub of the story"
"let C be the union of the sets A and B"
"The abstract summarizes the main ideas in the paper"
"Add all the people in this town to those of the neighboring town"