Lecture 4 --- Exercises
=======================


Solutions to the problems below must be sent to Submitty for grading.
A separate file must submitted for each problem.  These must be
submitted by 4 pm on Tuesday, January 31.


#. Write a program that assigns a string to the variable called
   ``phrase`` and then transforms ``phrase`` into a hashtag.  In other
   words, all words in ``phrase`` are capitalized, all spaces are
   removed, and a ``#`` appears in front.  Store the result in a
   variable called ``hashtag``.  Then print the value of both
   ``phrase`` and ``hashtag``.  Your program should start with

   ::
 
      phrase = 'Things you wish you knew as a freshman'

   and the output from the program (using :func:`print` function
   calls) should be

   ::

      The phrase "Things you wish you knew as a freshman"
      becomes the hashtag "#ThingsYouWishYouKnewAsAFreshman"

   Note that the output includes the quotation marks.

#. One of the challenges of programming is that there are often many
   ways to solve even the simplest problem.  Consider computing the
   area of the circle with the standard formula 

   .. math:: a(r) = \pi r^2

   Fortunately, we now have ``pi`` from the *math* module, but to
   compute the square of the radius we now can use ``**`` or
   :func:`pow` or we can just multiply the radius times itself.  To
   print the area accurate to only a few decimal places we can now use
   the string :func:`format` method or the :func:`round` built-in
   function, which includes an optional second argument to specify the
   number of decimal places.

   Write a short Python program that computes and prints the areas of
   two circles, one with radius 5 and the other with radius 32.  Your
   code must use ``**`` once and :func:`pow` once and it must use
   :func:`format` once and :func:`round` once.  The output should be
   exactly

   ::

       Area 1 = 78.54
       Area 2 = 3216.99