
Hour 8: Repeating an Action With Loops
NOTES AND CORRECTIONS
 On Page 132, the second exercise is a poor choice on my part because it
requires techniques that haven't been introduced in the first eight hours of
the book.
Here's a more suitable assignment: Write a short program
using loops that finds the first 400 numbers that are multiples of 13. The
solution for this exercise can be found in
Find13s.java and
Find13s.class.
SOURCE FILES
READER QUESTIONS
ACTIVITIES
 Solution #1: Rerepeat.java
and Rerepeat.class.
 Solution #2: FindPrimes.java
and Find400Primes.class.
To find out if a number is prime, you have to use the
% operator in Java, which returns the remainder of a
division operation. If you divide a number x by every
number from 2 through the square root of x , any
division that has a 0 remainder means that x is not
prime. This can be used to find the first 400 prime numbers. for
more information on primes, visit the Prime
Page.
