With pointed fangs I sit and wait; with piercing force I crunch out fate; grabbing victims, proclaiming might; physically joining with a single bite. What am I?

What is black when you buy it, red when you use it, and gray when you throw it away?

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?

What is harder to catch the faster you run?

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

You are an expert on paranormal activity and have been hired to locate a spirit haunting an old resort hotel. Strong signs indicate that the spirit lies behind one of four doors. The inscriptions on each door read as follows:

Door A: It's behind B or C
Door B: Its behind A or D
Door C: It's in here
Door D: It's not in here

Your psychic powers have told you three of the inscriptions are false, and one is true. Behind which door will you find the spirit?

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

Count the number of triangles in the picture below:

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

In the below-given picture of a pretty girl, there is something wrong. Can you find out what it is?