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

If in a code language, DISTANCE is written as IDTUBECN and DOCUMENT is written as ODDVNTNE, the how will THURSDAY be coded as in the same language?

Every words stands for unique digit that makes the arithmetic equation true

SEVEN + SEVEN + SIX = TWENTY.

What are the digits ?

During which month do people sleep the least?

What is harder to catch the faster you run?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

Christina is older than Kareena and Karishma. Katrina is older than Karishma and younger than Kareena. If Kareena has a brother named John, who is older than Christina, who's the youngest?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?

The ages of a father and son add up to 66.
The father's age is the son's age reversed.
How old could they be?
(3 possible solutions).