Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

You have a square. What you have to do is cut and reassemble the square such that you create a Red Cross sign that has the same volume as that of the square.

Some friends went on a vacation to a resort. It was raining heavily and it kept raining for thirteen days.

When it rained in the morning, the afternoon was beautiful and when it rained in the afternoon, the day was blessed with a clear morning.

Overall, the friends experienced eleven nice mornings and twelve nice afternoons. Can you find out the number of days they spent on vacation?

In which direction should the missing arrow point?

Solve this riddle by finding the odd one out from the rest.

What does a man do only once in his lifetime, but women do once a year after they are 29?

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

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?