A shopkeeper sells goods at the cost price but uses a 900 g weight in place of a 1 kg weight. What is the gain percentage?

💡 Solution & Explanation

The buyer pays for 1,000 g but receives only 900 g. So the seller gains 100 g on every 900 g actually given. Gain % = (100 ÷ 900) × 100 = 11.11%. Dividing by 1,000 instead gives 10%, which is wrong because the cost is for the 900 g handed over.