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

You stand in front of two doors. A guard stands next to each door. You know the following things: one path leads to paradise, the other leads to death. You cannot distinguish between the two doors. You also know that one of the two guards always tells the truth and the other always lies. You have permission to ask one guard one question to discover which door leads to paradise. What one question would you ask to guarantee you enter the door to paradise?

How can you make number one disappear by adding something to it?

The two towns are exactly 100 km apart. John leaves City A driving at 30 km/hr and Jacob leaves City B half an hour later driving at 60 km/hr. Who will be closer to City A when they meet?

Analyze and find the missing item in the sequence:
16, 06, 68, 88, __, 98

How many letters are in the alphabet?

Can you find a five letter word that is left with only two letters if one is removed?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

There is a place where if I stand up straight, I will still be considered sideways.

I travel all around the world but always stay in the corner. What am I?