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 181?
Choose the most appropriate option
A) 4360  B) 4890  C) 5280  D) 5740  E) 6320
100 + 102 +...+ 180 = 41*100 + (2+4...+80) = 41*100 + 2(1+2+...+40) =   41*100 + 2(40)(41)/2 = 140*41= 
<gadget id="calculator">140*41</gadget>
<output>5_740</output>
5740   The answer is 5740.
<result>D</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 181?