Can you circle exactly four of these numbers such that the total is twelve?

1 6 1
6 1 6
1 6 1
6 1 6

What number comes next in this sequence:
7 8 5 5 3 4 4 _

One night, a man runs away from home. He turns left and keeps running. After some time he turns left again and keeps running. Later, he turns left one more time and runs back home—but when he gets home, he finds a man in a mask. Who was the man in the mask?

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

What am I?

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

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

Can you count the number of matches in the picture below ?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

It's a 7-letter word.
If we remove 1 letter from it, it remains the same.
If we remove 2 letters from it, it remains the same.
If we remove 3 letters from it, it remains the same.
If we remove all the letters from it, still it remains the same.
What is it?