what is the 50th term of term of the series 1,3,6,10,15,21? Answers:  A) 1265  B) 1270  C) 1275  D) 1280  E) 1285
The series is like 1,1+2,1+2+3,1+2+3+4,....   so 50th term wil be 1+2+3+4+....50   sum of n natural numbers =n*(n+1)/2 where n is 50   answer wil be   25*51= 
<gadget id="calculator">  25*51</gadget>
<output>1_275</output>
1275   ANSWER:1275
<result>C</result>
what is the 50th term of term of the series 1,3,6,10,15,21?