Invalid number

Write a program that reads an integer number and calculates and prints
its square root. If the number is invalid or negative, print "Invalid
number". In all cases finally print "Good bye". Use try-catch-finally.
Non Number Exception

Write a method ReadNumber(int start, int end) that enters an integer
number in given range [start…end]. If an invalid number or non-number
text is entered, the method should throw an exception. Using this method
write a program that enters 10 numbers:
a1, a2, … a10, such that 1 < a1 < … < a10 < 100
Read All Text

Write a program that enters file name along with its full file path
(e.g. C:\WINDOWS\win.ini), reads its contents and prints it on the
console. Find in MSDN how to use System.IO.File.ReadAllText(…). Be sure
to catch all possible exceptions and print user-friendly error messages.
Download File Internet

Write a program that downloads a file from Internet (e.g.
http://www.devbg.org/img/Logo-BASD.jpg) and stores it the current
directory. Find in Google how to download files in C#. Be sure to catch
all exceptions and to free any used resources in the finally block.