By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?

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

Why is it against the law for a man living in Delhi to be buried in Mumbai?

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?

Imagine you are in a room with no windows or doors. How will you get out?

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

A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it. The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it. The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?

If "P" means "-", "Q" means "/", "R" means "+", and "S" means "*" then find the value of the following:

21 Q 7 R 9 S 10 P 13

Why did the Girl throw the butter out of the window?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?