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

What makes this number unique: 8,549,176,320?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

Why do you find that most of the buildings are deprived of the 13th floor?

Replace all '*' with digits 1, 2, 3, 4, 5 and 6 to make below statement true.

* *
x *
=====
* * *

If your uncle’s sister is not your aunt, what relation is she to you?

100 prisoners are stuck in the prison in solitary cells. The warden of the prison got bored one day and offered them a challenge. He will put one prisoner per day, selected at random (a prisoner can be selected more than once), into a special room with a light bulb and a switch which controls the bulb. No other prisoners can see or control the light bulb. The prisoner in the special room can either turn on the bulb, turn off the bulb or do nothing. On any day, the prisoners can stop this process and say "Every prisoner has been in the special room at least once". If that happens to be true, all the prisoners will be set free. If it is false, then all the prisoners will be executed. The prisoners are given some time to discuss and figure out a solution. How do they ensure they all go free?

Christina makes tasty toast in a small pan. After toasting one side of a slice, she turns it over. Each side takes 30 seconds. The pan can only hold two slices.
How can she toast both sides of three slices in 1 & 1/2 instead of 2 minutes?

Find the missing letter in the last circle logically in the given below picture.

Thirty friends were on a hiking trip when they decided to enjoy the bonfire. They assembled for it and agreed to play a game. For that, they divided themselves into five teams with seven members each, forming five rows.

How did they manage to achieve this formation?