Total natural no. from 11 to 90 which is divisible 7.  Options:
A) 9  B) 10  C) 11  D) 12  E) 13
these no. are 14,21,28,35,...,84.   these are in a.p series where a=14,d=(21-14)= 
<gadget id="calculator">(21-14)</gadget>
<output>7</output>
7,l=84   let these no. are n   nth no. =a+(n-1)d=14+(n-1)*7=(7n+7)   7n+7=84,n=11.   answer 11
<result>C</result>
Total natural no. from 11 to 90 which is divisible 7.