We are heading to the long weekend and just for a change I thought to challenge you mentally. So if you are having a cup of tea or coffee, finish it off and get ready to solve this problem.

This might be bit easy for people who deal every day in weighing something. Kirana shops and jewellers or maybe banker I can think of back of my mind or even passionate mathematician.

Imagine you have 10 stacks of 10 gold coins. All the coins in one stack are counterfeit, all the others are genuine. The genuine coin weigh 10 grams, and the counterfeit weigh 11 grams. Happily, these days we have digital weighing scale and you can weigh all the stacks and find the counterfeit.

But, as I am big fan of efficiency, I don’t want you to weigh all the stacks to find the counterfeit. You want to short circuit the process of finding this dodgy pile of counterfeit by the minimum possible number of weighing. How will you approach it, and how many weighing will you need to be sure you have identified the fake stack?

Neatest correct answer gets bragging rights.

I will share the correct answer tomorrow in the comment section.

All the best!