What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

Using mathematical symbols like +, -, and x in order to make the equations correct. Replace # with the above-given symbols.

9 # 8 # 7 # 6 # 5 # 4 = 91

The captain of a ship is telling you an interesting story and then poses a question. He says, “I have travelled the oceans far and wide. One time, two of my sailors were standing on opposite sides of the ship. One was looking west and the other one east. And at the same time, they could see each other clearly. Can you tell me how that was possible?”

Can you find out which number multiplied by itself will give the output as 12345678987654321?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

How many people must be gathered together in a room, before you can be certain that there is a greater than 50/50 chance that at least two of them have the same birthday?

Rearrange the letters in "new door" to make one word.