Exercises

1. Analyze the following code, and keep a log that tracks what value x references during each line of code. For example, it can look like this:

   Line 1: 3
   Line 2: 7
   Line 3: 2
   (etc. etc.)

   x = 3
   x = x + 4
   x = x - 5
   puts x
   x = x + x
   x = x + x
   x = x + x
   x = x * x
   x = "goodbye"

2. DEBUG: Look at the following code:

   first_number = 3
   puts first_number + second_number

   Can you guess what error you’ll get if you run the code? Now run the code yourself. What error message do you get?
3. DEBUG: Look at the following code:

   my_favorite_number = 9
   your_favorite_number = 1
   my_favorite_number + your_favorite_number = both
   puts both

   Fix the error by only changing line 3. The output should be 10.

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