6, 11, 21, 36, 56, 81, 111, 146, 186, ?  Answers:  A) 511  B) 711  C) 811  D) 231  E) 911
The pattern is + 5, + 10, + 15, + 20, + 25, + 30, + 35, + 40, + 45, + 50,....   Answer : 231.
<result>D</result>
6, 11, 21, 36, 56, 81, 111, 146, 186, ?