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

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

Eight of us go fourth, not back, to protect our king from an attack. What are we?

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

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

A detective visits his friend John just to discover that John's neighbour Dr Jacob was murdered. Dr Jacob, who is a mathematician wrote the murderer's name in a code word "Hcqtfz". There were five suspects
1. Ajit
2. Pankaj
3. Ganpat
4. Deenu
5. Hariya

The Detective was instantly able to find the murderer.
Can you?

Can you find the missing piece of the Porsche?

The following four words might seem abrupt to you. But you can make them meaningful by just adding vowels.
RDSH
GGPLNT
TMT
NN

Hint: All of them are vegetables.

Which number should replace the question mark?

What happened when the wheel was invented?

What goes through cities and fields, but never moves?