I am white when I am dirty, and black when I am clean. What am I?

If all Goats are Sheep and all Sheep are Deers, are all Deers Goats ?

Can you find out a way through which you can make five squares out of the given figure by moving just six match sticks?

Two friends were stuck in a cottage. They had nothing to do and thus they started playing cards. Suddenly the power went off and Friend 1 inverted the position of 15 cards in the normal deck of 52 cards and shuffled it. Now he asked Friend 2 to divide the cards into two piles (need not be equal) with equal number of cards facing up. The room was quite dark and Friend 2 could not see the cards. He thinks for a while and then divides the cards in two piles.

On checking, the count of cards facing up is same in both the piles. How could Friend 2 have done it ?

Its something that each of us devours,
Not just us but birds, beats, trees, and flowers,
Frets iron and nibbles steel,
Toil hard stones to meal,
Exterminates king, collapse town,
And blows the mountains down.

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

What Does this text mean:

important=important

Can you replace the question mark with the correct letter?

6 + 6 + 6 = N
7 + 7 + 7 = E
8 + 8 + 8 = R
0 + 0 + 0 = ?

Count the Triangle in the figure given below: