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

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

There once were seven dwarfs who were all brothers. They were all born two years apart. The youngest dwarf is seven years old. How old is his oldest brother?

Transform the word THINK into BRAIN while changing only one letter at a time in a manner that each of the word in the process is a real word!!!

What does below Rebus say?

XLR8

Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation. Conditions: Each must be used exactly once and no other numbers or symbols can be used.

What is the value of 1/2 of 2/3 of 3/4 of 4/5 of 5/6 of 6/7 of 7/8 of 8/9 of 9/10 of 1000?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain