A shopkeeper says he sells sugar at cost price, but he gives only 900 g every time a customer pays for 1 kg. What is his gain percentage?

Explanation

1. 01

   For every 900 g he gives, he is paid the cost of 1,000 g.

2. 02

   Gain = 100 g on a cost of 900 g.

3. 03

   Gain % = $\frac{100}{900} \times 100 = 11\frac{1}{9}\%$.