A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

In a university, a professor gave a set of three problems to the three brilliant students of his class. See the image for the questions.

I was speeding and ran through a stop sign, yet two traffic officers who were there do nothing about it.

why?

If I put in one bird per cage, I have one bird too many. If I put in two bird per cage, I have one cage too many. How many cages and birds do I have?

Using eight eights and addition only, can you make 1000?

In the given figure, you can see that four match sticks are used to form a square. Can you form five squares by using six matches?

What brings you down but never up?