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

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

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

A non-stop marathon is the shared favourite sport of three brothers.

*The oldest one is fat and short and trudges slowly on.
*The middle brother's tall and slim and keeps a steady pace.
*The youngest runs just like the wind, speeding through the race.

"He is young in years, we let him run!" the other two brothers explained, "'because though he is surely number one, he is second, in a way." Why is it?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

Find the missing letter in the last circle logically in the given below picture.

Replace the question mark with the correct number in the below-given picture?

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.

Can you find out the total number of triangles in the given figure?

A father's child, a mother's child, yet no one's son.

Who am I?