When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

If an electric train is travelling south, then which way is the smoke going?

What is the largest number you can write with just 3 digits?

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

How do you go from 98 to 720 using just one letter?

How many times can you subtract the number two from the number fifty?

There are two dice with empty faces in front of you and a marker. You can mark any number on each of the faces of the two dice, but you have to display all 31 days of the month using the two of them.

Which numbers will you mark on which dice so that you can easily depict all the dates of the month?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

"That Restaurant always remains crowded. This is the reason why nobody goes there".

Can you find a flaw in this statement?