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?

You have two bottles of pills marked with labels A and B. The pills are identical. The doctor has asked you to take one A pill and one B pill daily. You cant take more or less than that.

While taking out the pills one day, you took out one pill from A and by mistake took out two from B. You have no idea which pill is which now.

You cant throw away the expensive pills. What will you do now?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

Can you find the ages of a son, father and grandfather based on the following facts?
The sum of the ages of grandfather, father and son is 140 years.
The age of the son in months is the same as the grandfather in years.
The age of the son in days is the same as the father in weeks.

What does an Island and the letter T have in common?

You can hear me, but you can't touch or see me.

What am I?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

Next Number in the Series,

5, 16, 49, 104, ?