If you say my name, I will no longer exist. What am I?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

I am something people love or hate. I change peoples appearances and thoughts. If a person takes care of them self I will go up even higher. To some people I will fool them. To others I am a mystery. Some people might want to try and hide me but I will show. No matter how hard people try I will Never go down. What am I?

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?

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

What does this rebus picture identify?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

Give it food and it will live; give it water and it will die.

O_er_t_o_

Complete the missing letters of the given word.

Two boys were admitted to a school. When the headmaster asks them about their parents, they tell him that they have same parents (father and mother). On further inquiry, it turns out that they both share the same date for their birthday.

"Are you twins," ask the headmaster.
"No," replies the boys.

Is it possible?