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 99 and 171? Choose the correct choice from the following answers
A) 2820  B) 3440  C) 4860  D) 5560  E) 6720
100 + 102 + ... + 170 =   100*36 + (2+4+...+70) =   100*36 + 2*(1+2+...+35) =   100*36 + 2(35)(36)/2 =   100*36 + 35*36 = 135(36) = 4860   The answer is 4860.
<result>C</result>
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 99 and 171?