7^1+7^2+7^3+...........+7^2015 find out how many numbers present which unit place contain 3 ?	Select the correct option
A) 502  B) 503  C) 504  D) 505  E) 506
7^3,7^7,7^11,7^15,7^19.........7^2015 contains last digit=3.   Now,we see   3,7,11,15....2015 are in AP   tn=a+(n-1)d   2015=3+(n-1)4   2015=3+4n-4   4n=2016   n=504   ANSWER:504
<result>C</result>
7^1+7^2+7^3+...........+7^2015 find out how many numbers present which unit place contain 3 ?