What has no start, end, or centre?

You have four chains. Each chain has three links in it. Although it is difficult to cut the links, you wish to make a single loop with all 12 links. What is the fewest number of cuts you must make to accomplish this task?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

What number comes next in the series?

5 15 5 18 5 24 14 20 _

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?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

What is the last thing you take off before bed?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

What number comes next in this sequence:
7 8 5 5 3 4 4 _

How can a man go eight days without sleep?