What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

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

which number am I?

You measure my life in hours
I serve you by expiring
I vanish faster when I am thin
and slower when I am thick
The wind is my energy
What am I?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

John was a very careless driver, so his owner Jacob gave him an offer that he will get an incentive of Rs.30 for every bottle box he delivered without breaking it and he will be charged Rs.90 for every bottle box he broke. Jacob gave John 100 bottles-box to deliver. After delivery, Jacob paid John Rs.2400. How many bottles-box did John break?

Rearrange the letters in "new door" to make one word.

A thief enters a store and threatens the clerk, forcing her to open the safe. The clerk says, “The code for the safe is different every day, and if you hurt me you’ll never get the code.” But the thief manages to guess the code on his own. How did he do it?

Solve the equation by replacing the alphabet with numbers.

MOM + MOM + NO = BOOK=

Which digit occurred maximum times between the number 1 and 1000?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?