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?

A man is found hanging dead from the ceiling of a room. The room’s dimensions are 15 x 15 x 15. The man is only 6ft tall and the rope was only 2ft long. There are no windows and only one door to the room. The door is bolted shut from the inside, and a puddle of water is under the man. How did he kill himself?

I’m tall when I’m young, and I’m short when I’m old. What am I?

My location can be determined by the below rebus.
So where am i ?

If 21x = 79x, what is the value of x?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

You bought me for dinner but never eat me. What am I?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

Using eight eights and addition only, can you make 1000?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211