I make two people out of one. What am I?

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

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

I have a big mouth and I am also quite loud! I am NOT a gossip but I do get involved with everyone's dirty business.

Count the squares in the matchstick puzzle below?

what one word does the below rebus identifies?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

In the picture, you can see a chess board. On the top left position, the K marks a knight. Now, can you move the knight in a manner that after 63 moves, the knight has been placed at all the squares exactly once excluding the starting square?

In a concert, Christina is performing a dance show with her group.
At 10:00, she and her crew were dancing in an absolutely straight line. At that time Christina was standing in 4th position from both the front and back end of the row.

What was the size of her crew?

The day after tomorrow will be three days before Tuesday. Can you find out what is today?

Can you solve the maths in the below-given picture equation?