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

Who can jump higher than a Mountain?

It has five wheels, though often think four, You cannot use it without that one more, You can put things in it, you can strap things on top, You can't find it in the market, but you can still go shop. What is it?

Your mother’s brother’s only brother-in-law is asleep on your couch. Who is asleep on your couch?

In front of you, there are 9 coins. They all look absolutely identical, but one of the coins is fake. However, you know that the fake coin is lighter than the rest, and in front of you is a balance scale. What is the least number of weightings you can use to find the counterfeit coin?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

Find the missing number in the sequence below:

Women do it once a year after they turn 19 but men get to do it only once in a lifetime. What is it?

You can hear me, but you can't touch or see me.

What am I?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?