John is the son of Jacob.
So,
Jacob is the_____of John's father?

Find the smallest sentence with all the English alphabet.

What type of tree can I carry in my hand?

After teaching his class all about Roman numerals (X = 10, IX=9 and so on) the teacher asked his class to draw a single continuous line and turn IX into 6. The teacher's only stipulation was that the pen could not be lifted from the paper until the line was complete.

Transform the word THINK into BRAIN while changing only one letter at a time in a manner that each of the word in the process is a real word!!!

Can you find out the remainder when 3^300 is divided by 5?

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.

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

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

The dirtier I get, the whiter I look. Who am I?