I travel all around the world but always stay in the corner. What am I?

Two boys were admitted to a school. When the headmaster asks them about their parents, they tell him that they have same parents (father and mother). On further inquiry, it turns out that they both share the same date for their birthday.

"Are you twins," ask the headmaster.
"No," replies the boys.

Is it possible?

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

If,
9 * 8 * 7 = 65
8 * 7 * 6 = 50
7 * 6 * 5 = 37

Find
6 * 5 * 4 = ?

I have an eye but still cannot see.

Who am I?

What type of tree can I carry in my hand?

Solve the counting riddle by identifying the number of triangles in the given picture.

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

Jack was having a candle light dinner with his girlfriend. Suddenly a cold gush of wind entered through the open window and three of the ten candles were extinguished. Assuming that none of the other candles were extinguished.

How many candles are they left with in the end ?

Find the next number in the sequence

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