By selling a wristwatch for ₹2,430, a shopkeeper loses 10%. What was the cost price?

💡 Solution & Explanation

A 10% loss means the selling price is 90% of the cost price. So cost price = ₹2,430 × 100 ÷ 90 = ₹2,700. Check: 10% of ₹2,700 is ₹270, and ₹2,700 − ₹270 = ₹2,430. Adding 10% to ₹2,430 gives ₹2,673, which is wrong because the loss is a percentage of the cost, not of the selling price.