How can you make number one disappear by adding something to it?

John is asked to stand behind Jacob and Jacob is asked to stand behind John. Both of them feel confused about it and don't know what to do?

But it is quite possible, do you know how?

What is the Surname of Barbie Doll?

There are forty elephants and they have forty-fore heads. How can this be possible?

Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT

Can you move 2 matchsticks to form four equal sized squares.

Can you count the number of blocks in the picture below?

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?

Can you find the missing number in the third row?
35 20 14
27 12 18
5 2 ?

What does below chemistry rebus means?