Can you convert the number zero(0) into a positive number using just one mathematical operator ?

What does this rebus riddle means ?

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

Place a mathematical symbol between the numerals 5 and 9 in such a way that the resulting number is greater than 5 but smaller than 9.

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

A man has eighty-one cows ( numbered 1,2,3...81 as such). The beauty is that cow no. 1 gives 1ltr of milk, cow no. 2 gives 2ltrs of milk and so on. The man wants to equally distribute the cows among his nine sons so that each one of them gets the same quantity of milk.

Find The Next Number in the series:

12 13 15 17 111 113 117 119 123 ?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

Joseph organises an exotic office New year party at the beach to his important fellow employees.

Following are the important people that will come to the party

1. Joseph

2. Joseph 2 girlfriends- Carol Vanstone and Tracey Hughes

3. The sales head Clay Vanstone.

4. Clay Vanstone 2 associates.

5. Mr. Jeremy and his Secret Tab.

They all need to cross a small river to reach the beach, however, Joseph has got just one boat.

There are few rules for crossing the river.

1. The capacity of the boat is limited to just two people.

2. Clay Vanstone associates will not stay with Joseph without Clay Vanstone.

3. Carol Vanstone and Tracey Hughes will not stay with the Clay Vanstone without Joseph.

4. Mr. Jeremy would never leave the Secret Tab alone.

5. Secret Tab counts as a person.

6. Only Joseph, Clay Vanstone or Mr. Jeremy can drive the boat.

7. The two girlfriends Carol Vanstone and Tracey Hughes will not stay with the Clay Vanstone without Joseph.

8. No Associates would stay with Joseph without their Clay Vanstone.

9. Mr.Jeremy will not leave the Secret Tab alone.

Below toothpicks/matchsticks indicate the group of fishes moving from west to east direction. Can you make them move from east to west by just moving three toothpicks/matchsticks?