By selling 99 pens, a trader gains the cost of 9 pens. Find his gain percentage?
Answers:  A) 9 1/3%  B) 9 7/3%  C) 9 1/8%  D) 9 1/3%  E) 9 1/11%
Let the CP of each pen be Rs. 1.   CP of 99 pens = Rs. 99   Profit = Cost of 9 pens   = Rs. 9   Profit% = 9/99 * 100   = 9 1/11%   Answer: 9 1/11%
<result>E</result>
By selling 99 pens, a trader gains the cost of 9 pens. Find his gain percentage?