Can you replace the question mark with the correct number?

What do the following words have in common?

Assess
Banana
Dresser
Grammar
Potato
Revive
Uneven
Voodoo

What is the next number in the series?

15 29 56 108 208 ?

How can you throw a ball as hard as you can and have it come back to you even if it doesn't hit anything there is nothing attached to it and no one else catches or throws it.

I guess 76.8% of readers will like this riddle.

What's the least number of people should read this post?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

If you read clockwise, you can form a word by inserting three missing letters in the picture given below. Can you do it?

Can you place six X (crosses) in below board without making three in a row in any way ?

What do you answer even though it never asks you questions?

It can't be seen, can't be felt, can't be heard, and can't be smelt.
It lies behind stars and under hills, And empty holes it fills.
It comes first and follows after, Ends life, and kills laughter.
What is it?