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 word begins and ends with an E, but has only one letter?

In which direction should the missing arrow point?

It can't be seen, can't be felt, can't be heard, and can't be smelt.
It lies behind stars and under hills, And empty holes it fills.
It comes first and follows after, Ends life, and kills laughter.
What is it?

There’s a girl who has a large family. She has an equal amount of brothers and sisters, but each brother only has half as many brothers and sisters. What’s the correct amount of brothers and sisters?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

What is both possible and impossible at the same time?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

Mr Black, Mr Gray, and Mr White are fighting in a truel. They each get a gun and take turns shooting at each other until only one person is left. Mr Black, who hits his shot 1/3 of the time, gets to shoot first. Mr Gray, who hits his shot 2/3 of the time, gets to shoot next, assuming he is still alive. Mr White, who hits his shot all the time, shoots next, assuming he is also alive. The cycle repeats. If you are Mr Black, where should you shoot first for the highest chance of survival?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?