Here’s a collection of 5 tricky Brain Teasers.  If you get stuck, click the Show Answer button to reveal the solution.  Let us know if you figured them out in the comments below, but try to hide the answer from others.

1  The Disappearing Dollar

Three travelers decide to stay at a hotel and are told that their rooms will cost $10 each so they pay $30. Later, the clerk realizes that he made a mistake and should have only charged them $25. He gives a bellboy $5 to return to them but the bellboy is dishonest and gives them each only $1, keeping $2 for himself. So the men actually spent $27 and the bellboy kept $2. What happened to the other dollar from the original $30?

2  What’s in the box?

Three closed boxes have either apples, oranges, or both, and they are labeled apples, oranges, and both. However, you’re told that each of the labels are wrong. You may reach into one of the boxes and pull out only one fruit. Which box should you remove a fruit from to determine the contents of all three boxes?”

3  Find the counterfeit

You are given 8 coins and told that one of them is counterfeit. The counterfeit one is slightly heavier than the other seven. Otherwise, the coins look identical. Using a simple balance scale, how can you determine which coin is counterfeit using the scale only twice?

4  Cold to Warm…

How do you get from the word cold to the word warm in four steps, changing only one letter at a time but still creating real words?

5  What’s the number?

Look at the numbers below… what is the value of X?

8809 = 6
7111 = 0
2172 = 0
6666 = 4
1111 = 0
3213 = 0
7662 = 2
9313 = 1
0000 = 4
2222 = 0
3333 = 0
5555 = 0
8193 = 3
8096 = 5
1012 = 1
7777 = 0
9999 = 4
7756 = 1
6855 = 3
9881 = 5
5531 = 0
2581 = ?

Solutions…

1.

There is no missing dollar from the original $30 because after getting $1 back, the three travelers had paid a total of $27 for their room ($9 each), not $30. Out of that $27, the hotel has $25 and the clerk kept the remaining $2. If you still want to work from the original $30, the travelers have $3, the hotel has $25 and the bellboy has $2. The misleading part is adding the bellboy’s $2 to the $27, when in fact it should be subtracted.

2.

The one labeled both. Since you know it’s labeled incorrectly, it must have all apples or all oranges. After you determine what it contains, you can identify the other two boxes by the process of elimination.

3.

First, weigh three coins against three others. If the weights are equal, weigh the remaining two against each other. The heavier one has the counterfeit.  If one of the groups of three is heavier, weigh two of those coins against each other. If one is heavier, it’s the counterfeit.  If they’re equal weight, the third coin is the counterfeit. 

4.

cold –> cord –> word –> worm or ward –> warm

5.

X = 2, which is the number of closed circles in the 4 digits. 0, 6 and 9 each have one, 8 has 2.