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In an interview I was asked the below puzzle as the last question:
A person goes to a shop to buy something and the ensuing conversation with the shopkeeper is mentioned below...
Person: How much does one cost?
Shopkeeper: It is Rs10.
Person: How much for 14?
Shopkeeper: Rs20.
Person: How much for 114?
Shopkeeper: Rs30.What is the person trying to buy?
I couldn't answer. Still figuring it out.
This is a classic puzzle. I was so sure that it must already have been asked here on Puzzling, but I have been unable to find a duplicate after a short keyword search (this question is perhaps the closest...). The answer is:
house numbers (i.e. the usually metallic numerals that can be mounted on a wall or fence to indicate the house number). Usually, these are costed at a certain price per digit - in the case of your question, Rs10 for a single digit.
This way, one numeral (e.g. for a house numbered 1-9) costs Rs10. But the two numerals required for a house numbered '14' would cost Rs20 (2 times Rs10, for a 1 and a 4) and the total cost of three numerals for a house numbered '114' would be Rs30 (3 times Rs10, for two 1s and a 4).
