What is in seasons, seconds, centuries and minutes but not in decades, years or days?

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

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

Two girls were born to the same mother, on the same day, at the same time, in the same month and year and yet they're not twins. How can this be ?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

You need to remove two matchsticks to make the below equation true. Can you do it ?

What country can make you shiver?

How many times can you subtract the number two from the number fifty?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

Can you make four (4) nines (9) equal 100?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C