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

Can you tell a 3D object that has just two surfaces?

Which Travels Faster? Solve below famous picture riddle:

Two fathers and two sons went fishing one day. They were there the whole day and only caught 3 fish. One father said, that is enough for all of us, we will have one each. How can this be possible?

The below given figure comprises of a pattern through which you can determine the missing letter. Can you push your mind to find the pattern and add the missing letter?

Consider this: Arnold Schwarzenegger has a big one. Michael J. Fox has a small one. Prince doesn’t have one. The Pope has one but never uses it. Bill Clinton has one and uses it all the time. What is it?

John is 45 years older than his son Jacob. If you find similarities between their ages, both of their ages contain prime numbers as the digits. Also, John's age is the reverse of Jacob's age.

Can you find their ages?

Why do we preferably have round manhole covers and not square ones?

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?