c. The test is $i<=10, so when the test is finally false, $i must be 11. If you got this one wrong, don't worry. It's such a common mistake that it even has a special name among programmers: a fence post error or an off-by-one error.
Activities
Modify Listing 3.1 to keep playing the game until a successful guess is made.
Listing 3.3, as it is written, is actually quite inefficient at finding primes. For example, it analyzes all the even numbers above 2—which cannot possibly be prime. Make additions to the algorithm to make the Primes program more efficient.