Rotating Coins Around Coins

You have two coins of equal size on a table, situated end to end vertically. If you roll the top coin around the bottom coin until it returns to its original position, how many times will it have rotated?

Twice. See this video for more details.

Posted in Brain Teasers

Useless Keys

What keys don’t unlock any doors?

Piano keys, keyboard keys, monkey, donkey, turkey, jockey, hockey, doohickey, malarkey and passkey. There may be others, but you get the drift.

Posted in Brain Teasers

You Melted My Ice

A full glass of water with a single ice cube sits on a table. When the ice has completely melted, will the level of the water have increased, decreased or remain unchanged?

The water level remains unchanged because the ice cube displaces its own weight. If you’re not convinced, read Archimedes’ Principle, which states that any floating object displaces its own weight of fluid. Still not convinced? Here are a few more sources.

Posted in Brain Teasers

Two Four Three Five Six

0 2 4 3 5 6 8 9 7 11 10 12 13 14 15 16 18 17 20 21 22 19 24 23 26 25 28 29 27

What is the next number in the sequence?

31. The tenth number is 10 + 1 = 11. The twentieth number is 20 + 1 = 21, therefore the thirtieth number is 30 + 1 = 31.

Posted in Brain Teasers
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The Secret Lair

A secret lair has a code to only allow members to enter. The person wanting to enter says a random number, then is told a number in response. In order to enter they must say the correct third number. Here are sequences that allowed entrance.

1 3 5
27 11 6
9 4 4

What’s the third number of this series?

16 7 ?

Five because s-e-v-e-n has 5 letters. The first number can be anything, the second number is the number of letters in the first number, and the third number is the number of letters in the second number.

Posted in Brain Teasers

How Can You Pass the Tree

A car is on a narrow road with a tree in the middle of it. How can the car pass the tree?

The tree is in the middle of the road as measured by length, not in the middle of it by width. In other words, the tree is growing on the side of the road, but it is equidistant from either end of the road, and therefore in the middle.

This makes it quite easy to pass the tree as you just drive on the road, unless you’re texting and you run into said tree. If this is the case, stop texting.

Thanks to everyone’s input on this one!

Posted in Brain Teasers

Lies Behind Stars

It cannot be seen, it cannot be felt,
Cannot be heard, cannot be smelt,
Lies behind stars and under hills,
And empty holes it fills.
Comes first follows after,
Ends life kills laughter.

Darkness.

Posted in Riddles

Border Plane Crash

A plane crashed on the border or US and Canada. Where do they bury the survivors?

Nowhere, you don’t bury survivors.

Posted in Brain Teasers

Who May Enter?

A green glass door admits only certain objects. Apples and balls are allowed, but pears and bats aren’t. What determines whether an item can enter?

All words with a repeated letter are allowed. Green glass door, apple and ball.

Posted in Brain Teasers

Many are Perplexed While Seeking Me

Many get perplexed in life while seeking me. Others put their life in danger and others give up. If you find me you are satisfied. What am I?

Hint: It is in every house.

You. Hundreds of books have been written about people searching for themselves. Some methods are quite dangerous. Still others give up. But if you figure out who you are, you will be satisfied.

Lastly, the word you is in the phrase everY hOUse.

Posted in Riddles