It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

If Japan and Panama decided to merge into a single country, probably people will name it Japanama.

Can you think of two more such country's unions that could produce similar names like Japanama by overlapping their three letters?

All of Jacob's shoes are red except two.
All of Jacob's shoes are green except two.
All of Jacob's shoes are yellow except two.

How many shoes does Jacob have?