using four eights (8) and a one (1) and one mathematical symbol , create the number 100

What does this mean?

CCCCCCC

I am white when I am dirty, and black when I am clean. What am I?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

Eight of us go fourth, not back, to protect our king from an attack. What are we?

In a contest, four fruits (an apple, a banana, an orange, and a pear) have been placed in four closed boxes (one fruit per box). People may guess which fruit is in which box. 123 people participate in the contest. When the boxes are opened, it turns out that 43 people have guessed none of the fruits correctly, 39 people have guessed one fruit correctly, and 31 people have guessed two fruits correctly.
How many people have guessed three fruits correctly, and how many people have guessed four fruits correctly

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

How far can you walk into the woods?

A boy purchased a book from a bookkeeper and gave him $100.
The cost of the book is $50 but the bookkeeper has no change, so he gets the change from the next shop and returns the boy his $50.

After some time the next shopkeeper came with the $100 note and told the bookkeeper that the note was a fraud, so he took the money back.

How much loss did the bookkeeper face?

By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?