Sum of even numbers between 15 and 25 is
Choose the correct choice from the following choices.
A) 70
B) 80
C) 130
D) 100
E) 120
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)/2we get, =50   So 16 + 18 + .......24 = 2 Ã— 50 = 100   ANSWER IS 100
<result>D</result>
Sum of even numbers between 15 and 25 is