By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

John is 45 years older than his son Jacob. If you find similarities between their ages, both of their ages contain prime numbers as the digits. Also, John's age is the reverse of Jacob's age.

Can you find their ages?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

Can you name four days which start with the letter 'T'?

The more you take me, the more you leave me behind.
Who Am I?

Why is a river so rich ?

our enemy challenges you to play Russian Roulette with a 6-cylinder pistol (meaning it has room for 6 bullets). He puts 2 bullets into the gun in consecutive slots, and leaves the next four slots blank. He spins the barrel and hands you the gun. You point the gun at yourself and pull the trigger. It doesn't go off. Your enemy tells you that you need to pull the trigger one more time, and that you can choose to either spin the barrel at random, or not, before pulling the trigger again. Spinning the barrel will position the barrel in a random position.

Assuming you'd like to live, should you spin the barrel or not before pulling the trigger again?

Why is the Hole below a Lock?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.