for any positive integer n , the sum of the first n positive integers equals n ( n + 1 ) / 2 . what is the sum of all the even integers between 1 and 100 ?
"average of the set : ( largest + smallest ) / 2 = ( 100 + 2 ) / 2 = 51 ; # of terms : ( largest - smallest ) / 2 + 1 = ( 100 - 2 ) / 2 + 1 = 50 the sum = 51 * 50 = 2550 answer : e"
add(divide(subtract(subtract(100, 1), add(1, 1)), 2), 1)