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

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

What you cannot hold but it is yours?

Solve the following series:
AZ, GT, MN, __, YB

Buy me, smell me or deliver me, I do not change.

Who am I?

Seven Robbers robbed a bank and hide the coins in a lonely place.
They decide to divide the money equally the next morning. Two greedy robbers decided to cheat the others and reach the place at night. They equally divided the coins between them, one coin left. So they called another robber and then they decided to divide equally among the three. Sadly again one coin left. The same thing happened to the 4th 5th and the 6th robber.
However, when the 7th robber reached in the morning, they can divide the coins equally.

How many coins were there in total?

Your job is to measure 45 minutes if you have only two cords and matches to light the cords.

1. The two cords are twisted from various materials, so their different segments can burn at different rates.
2. Each cord burns from end to end in exactly one hour.

Describe your way of measuring the 45 minutes.

If all Goats are Sheep and all Sheep are Deers, are all Deers Goats ?

A man stands on one side of a river, his dog on the other. The man calls his dog, who immediately crosses the river without getting wet and without using a bridge or a boat. How did the dog do it?