Will the Programm work if the user enters a zero?

Eine gute Antwort könnte sein:

Hmmm... it should, since zero has a square root.

Example Output

It is good to get into the habit of worrying about what happens with special values. The Programm does happen to work with zero. Here is the output of the Programm for several values: 

C:\chap19>java SquareRoot
Enter the number:
0.0000000000000000000003
The square root of 3.0E-22 is 1.732050807568877E-11

C:\chap19>java SquareRoot
Enter the number:
-12
Please enter a positive number

C:\chap19>java SquareRoot
Enter the number:
144.0
The square root of 144.0 is 12.0

FRAGE 20:

Suggest a few other values with which the Programm should be tested.