The more of this there is, the less you see. What is it?

What is the next number in the series?

15 29 56 108 208 ?

I can turn polar bears white.
I can make anyone dance.
I can make everyone cry
I can make your hands clap
I can make you thin.
I can make you smile.
I can make you smile

Can you guess the riddle?

What building has the most stories?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

If 24H in a D => 24 hours in a day.
What does "64S on CB" stand for?

Rearrange the letters in "new door" to make one word.

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

How many words can a pen with half refill write?

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?