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Mind Teasers : Extremely Hard Civil Services Problem

Difficulty Popularity

( ) + ( ) + ( ) + ( ) + ( ) = 30
This is what you have for equation. The following are the numbers that you can use to fill in the brackets:
1, 3, 5, 7, 9, 11, 13 and 15

You can repeat the numbers if required. The resulting sum should be 30.

This question appeared in the UPSC final examination in December 2013. Out of all the people who appeared, only one guy was able to solve this namely Gaurav Agarwal.

Can you solve it?

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  • Views : 80k+
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Mind Teasers : Two Men One Question Puzzle

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Imagine that you are travelling to a village. You happen to reach a point in the road where there is a fork. There are two ways that you can go into but only one amongst them is correct and leads to the village. You happen to see two men standing on the fork and you can ask them for the direction. To your bad luck, one amongst the two men always lies and the other one always says the truth. But you do not know who is a liar and who is not. At that point of the situation you are allowed to ask only one question to any one of the men standing there.

What question will you ask?

  • Views : 80k+
  • Sol Viewed : 20k+

Mind Teasers : Tough Number Problem Riddle

Difficulty Popularity

Find smallest number that you can write using all the vowels(A,E,O,I,U) exactly once?

  • Views : 80k+
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Mind Teasers : Logical Bank Brain Teaser

Difficulty Popularity

A bank customer had Rs.100 in his account. He then made 6 withdrawals, totaling Rs.. He kept a record of these withdrawals, and the balance remaining in the account, as follows:

Withdrawals Balance left
Rs.50 Rs.50
Rs.25 Rs.25
Rs.10 Rs.15
Rs.8 Rs.7
Rs.5 Rs.2
Rs.2 Rs.0
Rs.100 Rs.99


Why are the Totals not exactly right ?

  • Views : 80k+
  • Sol Viewed : 20k+

Mind Teasers : Switch Chances Interview Problem

Difficulty Popularity

You are sitting in front of your interviewer. He gives you three envelopes. One of them contains an offer letter and the other two are empty. You pick up one of them. Now, the interviewer opens up one of the envelope lying on the table and you find out that it is blank.

Now, he gives you a chance to switch your envelope with the one on the table. Would you switch it? Why or why not?

  • Views : 70k+
  • Sol Viewed : 20k+

Mind Teasers : Most Popular Logical Puzzle

Difficulty Popularity

Outside a room there are three light switches. One of switch is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb ??

By Admin
  • Views : 80k+
  • Sol Viewed : 20k+

Mind Teasers : Spatial Trivia Physics Puzzle

Difficulty Popularity

As shown in picture, there are four gears with the following specification
* Gear A has 60 teeth
* Gear B has 40 teeth
* Gear C has 20 teeth
* Gear D has 60 teeth
* Every minute, Gear B makes 15 complete turns.

What is the relative speed of Gear A and Gear B?

By Admin
  • Views : 80k+
  • Sol Viewed : 20k+

Mind Teasers : 12 Sum Matchstick Brain Teaser

Difficulty Popularity

We have arranged matchsticks in a manner that all the first row, second row, first column and third column contain 12 matchsticks each. Can you remove 4 matchsticks and rearrange all the remaining matchsticks that we are still left with 12 matchsticks in the first row, second row, first column and the third column.


  • Views : 80k+
  • Sol Viewed : 20k+

Mind Teasers : Palindrome Number Riddle

Difficulty Popularity

There can be myriad ways to create a palindrome. One day, I thought of making my own palindrome. I thought of a number and then decided to add the reversed number to it. Sadly, I did not get a palindrome.

So I kept repeating this step and eventually I succeeded in creating a palindrome. I don't know if you can always create a palindrome using this method but I was able to generate one of four digits.

Can you tell me the number at which I started?

  • Views : 60k+
  • Sol Viewed : 20k+

Mind Teasers : Brain Twister For Kids

Difficulty Popularity

A clever robber breaks into a closed bank where he finds a clerk. He asks password of the safe from the clerk while pointing a gun on his forehead. Out of fear, the clerk manages to blurt out, “Every day, the password of the safe is changed. I can help you but please point away the gun as if you kill me, you will never be able to crack the password.

The robber ties the clerk on a chair and insert a cloth in his mouth. He then easily opens the safe after inserting the code and takes all the money before he flees.

How did he know the password ?

  • Views : 70k+
  • Sol Viewed : 20k+

Mind Teasers : Pirates Probability Brain Teaser

Difficulty Popularity

You are stuck with the pirates who might even kill you on board. They give you a chance to survive. There are hundred black rocks and hundred red rocks. There are two empty sacks which are labelled as heads and tails respectively. You have to divide the rocks in two bags as per your wish. Then a fair coin will be flipped. If its heads, you will have to pick a rock on random from the sack labelled heads and if its tails, you will pick up from the tails sack. If you pick up a black rock, you will be freed and if you pick up a red rock, you will be killed.

How will you distribute the rocks so that your chances of survival are the best?

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