Can you find out which number multiplied by itself will give the output as 12345678987654321?

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?

Rectify the following equality 101 - 102 = 1 by moving just one digit.

Replace the (?) with the correct mathematical signs to make the expression equal to 59.

18 ? 12 ? 4 ? 5 = 59

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

Using Only Five 5's and any mathematical operator make sum as 37

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

What does this mathematical rebus means ?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

What is next number in the pattern below:

131 517 192 123 ?