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

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?

I have branches, but no fruit, trunk or leaves. What am I?

John bought 150 chocolates but he misplaced some of them. His Father asked him how many chocolates were misplaced.
He gave the following answer to him:
If you count in pairs, one remains
If you count in threes, two remain
If you count in fours, three remain
If you count in fives, four remain
If you count in sixes, five remain
If you count in sevens, no chocolate remains.

Can you analyze the statements and tell us how many chocolates were lost?

I cannot talk, but I always reply when spoken to. What am I?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

Here is a mathematical expression that also secretly tells a movie name. What movie is that?

Which tank will fill first?

What is both possible and impossible at the same time?