What is always in front of you but can’t be seen?

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

When monkey rotate the gear, which mark will be hit 1 or 2 ?

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

Can you decipher these quotes by Albert Einstein?
Blf xzm mvevi hloev z kilyovn lm gsv ovevo lm dsrxs rg dzh xivzgvw.

One day, John and his friends were playing around. Jacob hit something with a Pin and it popped. John's dad came into the room that very moment, but he wasn't mad. In fact, he was smiling. What did Jacob hit?

In a secret society, a buried chamber can be accessed only via a secret password. The password is seven characters long and comprises of just letters and numbers.

You find a code that can help you in cracking the password. The code says "You force heaven to be empty".

Can you deduce the password from that?

Two Twins Jack and Jill were standing back to back and suddenly they started running in opposite direction for 4 kilometres and then turn to left and run for another 3 kilometres.

what is the distance between the Baggio twins when they stop ?

By moving exactly three matchsticks can you make the below equation true.It can be solved by 3 ways.

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?