81 x 9 = 801. What must you do to make the this equation true?

Which alphabet is a part of our body?

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?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

You are a cab driver who pools passengers. You pick 3 people from a destination and drop 1 after an hour. 2 people climb aboard at the same time and you drop 3 at the next destination. After some time, you pick 2 passengers only to drop 1 after a short distance where 3 more passengers climb up the cab. You leave the rest of the passengers one by one to their destination and then come back home.

Can you tell the eye color of the cab driver?

Solve this riddle by finding the odd one out from the rest.

What has no start, end, or centre?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

A man dies of old age on his 25 birthday. How is this possible?

Which country gets ill every time?