Take away the whole and some still remain. What is it?

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?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

You find yourself in a strange place guarded by two guards.One of the guard always say truth while other always lies.You don't know the identity of the two.You can ask only one question to go out from there. What should you ask?

If an electric train is travelling south, then which way is the smoke going?

What does this below rebus puzzle mean?

On her drawing table, Sayna lit 12 coloured candles. A few seconds later she blew two candles off.

How many candles Sayna have at the end?

A bag contains 64 balls of eight different colours. There are eight of each colour (including red). What is the least number you would have to pick, without looking, to be sure of selecting 3 red balls?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

You walk into a room where there are three primates held in their respective cages:
1) A lion who is eating the flesh of a goat.
2) An orangutan who is playing with blocks.
3) A donkey who is sitting idle.

Who is the most intelligent primate in the room?