Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

What runs around the whole yard without moving?

What number divided by 4 is the same as that number minus 4?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

What does the below image rebus riddle means ?

I can sizzle like bacon,
I am made with an egg,
I have plenty of backbone, but lack a good leg,
I peel layers like onions, but still remain whole,
I can be long, like a flagpole, yet fit in a hole.

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it. The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it. The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?

What is the word or phrase?

You can hear me, but you can't touch or see me.

What am I?