There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

What is next number in the pattern below:

131 517 192 123 ?

Rearrange the letters in "new door" to make one word.

A girl says this to her best friend: “I was born in 1955, and I celebrated my 17th birthday last weekend.” Her best friend thinks she’s lying, but she’s actually correct. How is that possible?

Christina, Allison and Lena are 3 daughters of John a well-known Mathematician, When I asked John the age of their daughters. He replied "The current age of her daughters is prime. Also, the difference between their ages is also prime."

How old are the daughters?

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?

The day before yesterday I was 25 and the next year I will be 28. This is true only one day in a year. What day is my birthday?

Count the number of lines in the image below ?

When is the top of a mountain similar to a savings account?

Count the Triangle in the figure given below: