Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

Can you count the number of lines in the below picture?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

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.

What runs around the whole yard without moving?

I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?

The king of Octopuses has servants who have six, seven or eight legs. The distinguishing characteristics of the servants is that the one with seven legs always lie but the one with either six or eight legs speak the truth always.

One day, four servants meet and converse:

The black one says, 'We have 28 legs altogether.'

The green one says, 'We have 27 legs altogether.'

The yellow one says, 'We have 26 legs altogether.'

The red one says, 'We have 25 legs altogether.'


Can you identify the colour of the servant who is speaking the truth?

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

There are six people in a family namely M, N, O, P, Q and R.

R and O are brother and sister.

N is the brother of Q's husband.
P is the father of M and grandfather of R.

How many male members are in the family?

What happened when the wheel was invented?