Before Mount Everest was discovered, what was the highest mountain in the world?

I add 5 to 9 and get 2. The answer is correct, so what am I?

A man was gazing through the window of the 23rd floor of the building. He suddenly opened the window and jumped on the other side of the window. On landing on the floor, there was not a sheer mark of injury on him.

How can that be possible if he did not use any kind of parachute and did not land on a soft surface?

Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M

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?

Can you find the odd number in the following five choices?

1) 482636
2) 259807
3) 865195
4) 104739
5) 391744

Find the next number in the sequence

1, 2, 6, 21, 88, __?

What demands an answer, but asks no questions

An explorer goes on an exposition in the jungle. He sets up camp in the middle of the jungle. The next morning he sees something with a head and a tail, but he is not afraid. What did he see in his bag?

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