If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

John is looking at Jenifer, but Jenifer is looking at Jacob. John is married, but Jacob is not.

Is a married person looking at an unmarried person ?

What is the difference between a jeweller and a jailer?

Can you figure out the logic I used to decide the order of the following words:
gun, shoe, spree, door, hive, kicks, heaven, gate, line, den

A container contains 100 eggs. They can be either fresh or rotten. What is sure is the fact that there is at least one fresh egg in that container.

If you are asked to pick two eggs randomly from the container, at least one of them will be rotten.

Can you calculate how many eggs in that container are fresh?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

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

Can you find out a way through which you can make five squares out of the given figure by moving just six match sticks?

Decode the below four famous ciphers:

8P of the SS
1M of the E
1S of the SS
60M in 1H

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?