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

What is the next number in the series?

15 29 56 108 208 ?

You find yourself in a strange place guarded by two guards.One of the guard always say truth while other always lies.You don't know the identity of the two.You can ask only one question to go out from there. What should you ask?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

Spot what is wrong here in below Picture?

What does this rebus means ?

What is the next number in this matchsticks series riddle?

John Went to the nearby store in a Mall to buy something for her home. Below is the conversation between the two:

John: How much for the one?
Shopkeeper: It is $2
John: How much for the Eleven?
Shopkeeper: It is $4
John: How much for the Hundred?
Shopkeeper: It is $6.

What is John buying?

Count the number of balls in picture below: