Sum of even numbers between 15 and 25 is	Choose the correct choice from the following:
A) 70
B) 80
C) 130
D) 100
E) None
Explanation: 16 + 18 + .......24.   Taking 2 common we get = 2 ( 8 + 9 + 10 +.....+ 12)   Sum of n natural numbers upto 12   8 + 9 + 10 +.....+ 12 = (1 + 2 + 3 + ......+ 12) - ( 1 + 2 + 3 + ....+ 7)   By applying the formula for the first n natural numbers sum n(n+1)/2 we get, 12(12+1)/2−7(7+1)/2=50   So 16 + 18 + .......24 = 2 × 50 = 100   Correct Option: 100
<result>D</result>
Sum of even numbers between 15 and 25 is