Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

Solve the following series:
AZ, GT, MN, __, YB

What building has the most stories?

You need to cut a round cake into eight equal pieces with just 3 cuts. Can you do it?

There are three boxes which are labeled as Rs100, Rs150, and Rs200. One box contains two notes of Rs. 50. The second box contains one note of Rs50 and one note of Rs100 The third box contains two Rs. 100 notes. All boxes are labeled incorrectly.

What is the minimum number of boxes you must check in order to label all boxes correctly?

I am the fastest animal but cannot climb the tree. What am I?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

How many letters are in the alphabet?

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

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?