What work can one never finish?

Next Number in the Series,

5, 16, 49, 104, ?

John went to meet his friend Jacob, but when he was about to reach the main gate, John notices that Jacob had a mighty dog who was fastened to the tree. The chain is long enough that it allows the dog to reach the main gate.

How can the John reach the main gate?

I am the fastest animal but cannot climb the tree. What am I?

Your job is to measure 45 minutes if you have only two cords and matches to light the cords.

1. The two cords are twisted from various materials, so their different segments can burn at different rates.
2. Each cord burns from end to end in exactly one hour.

Describe your way of measuring the 45 minutes.

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

What does this simple rebus mean?

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

Why do Chinese men eat more rice than Japanese men do ?

What goes through cities and fields, but never moves?