Homework 11, due Wednesday, February 16, 2011
 Reading from our book: Read pages 82 to the top of p. 86.
 Do Problem 4 on p. 89 and Problem 7 on p. 90. [Note: the statement of problem 4 ends with "reduce 7^1000 and mod 3" but the "and" is a typo; it should say "reduce 7^1000 mod 3".]
 For a class discussion, bring in a piece of junk mail with a bar code
on it if you can. The code that we'll need has bars of only two lengths (short bars and long bars). There are other bar codes that the post office uses sometimes with more bars of more than two lengths, but these aren't what we'll be looking at.