The centre of the third figure is empty. What digit should fit inside?

A man says, "Brothers and sisters, have I none, but that man's father is my father's son." Who is that man?

Why do we preferably have round manhole covers and not square ones?

What breaks yet never falls, and what falls yet never breaks?

What is a word made up of 4 letters, yet is also made up of 3. Sometimes is written with 9 letters, and then with 4. Rarely consists of 6, and never is written with 5.

How can you write nineteen in a manner that if we take out one, it becomes twenty?

The following four words might seem abrupt to you. But you can make them meaningful by just adding vowels.
RDSH
GGPLNT
TMT
NN

Hint: All of them are vegetables.

What has one eye, but can’t see?

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

A 52% bias toss for head using the 51% tail bias coin was done to obtain a fair result.

Can you find how bias is the floor in this case?