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

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

What common phrase is represented by the below lines

Easy going:
Weak, 'I'm going.'
Tough, 'I'm staying.'

Medium going:
Weak, 'I'm going.'
Tough, 'I'm staying.'

Tough going:
Weak, 'I can't do it, I'm staying!'
Tough, 'Let's get going.'

Why is it against the law for a man living in Delhi to be buried in Mumbai?

Today is a very icy and cold morning in Newcastle. Mr Shearer, an office bus driver arrived to pick up the employees from the last stop. Shearer suddenly remembers that he needs to pick a newly joined 4miles to the north. Mr Shearer lost his direction compass, a few minutes later Shearer is able to figure that he is moving in the correct direction i.e. north. How did Shearer know that he is moving in the correct direction?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

A mathematician couple was having a Frappuccino in Starbucks sitting opposite to each other. Suddenly the guy noticed the text written on the paper in front of them and exclaimed that it was wrong. The girl denied it and said it is appropriate. Both are correct. What is written on the paper?