The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

I was speeding and ran through a stop sign, yet two traffic officers who were there do nothing about it.

why?

A sea diver is a real show-off. He showed everyone that he can hold his breath underwater for 15 minutes.

I went to the diver and told him that I can be underwater for double the time i.e 30 minutes.
He responded that he will give me 100$ if I would be able to do it. I won 100$.

What did I do?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

I welcome the day with a show of light, I stealthily came here in the night. I bathe the earthy stuff at dawn, But by noon, alas! I'm gone.

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

What does a man do only once in his lifetime, but women do once a year after they are 29?

In the figure, you can see nine stars. What you have to do is connect all of them by using just four line and without lifting your hand i.e. in a continuous flow.

You have to fill the below given grid in a manner that every row and column contains the digits 1 to 6. Also, make sure that the squares that are connected with each other must contains the same digit.