What numbers should go on the bottom line?
3 6 9 15
8 2 10 12
11 8 19 27
19 10 29 39
? ? ? ?

Three ants are sitting at the three corners of an equilateral triangle. Each ant starts randomly picks a direction and starts to move along the edge of the triangle. What is the probability that none of the ants collide?

What is black when you buy it, red when you use it, and gray when you throw it away?

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

How could a baby fall out of a twenty-story building onto the ground and live?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

What number when divided in half becomes zero?

What do you see in the given picture?

Prove that twice of ten is the same as twice of eleven.