# Challenges Remember the rules for this are - Try to use only the information given up to this point in this book. - Try not to give up until you've given it a solid attempt ## Challenge 1 What will this program output when run? Write down your guess and then try running it. ```java,editable void main() { String first = "1"; String second = "2"; String result = first + second; IO.println(result); } ``` ## Challenge 2 What will this program output when run? Write down your guess and then try running it. ```java,editable void main() { String first = "1"; int second = 2; IO.println(first + second); } ``` ## Challenge 3 What will this program output when run? Write down your guess and then try running it. ```java,editable void main() { char first = 'a'; String second = "b"; String third = "ab"; IO.println((first + second).equals(third)); } ``` ## Challenge 4 Make it so this program will output `abc` by only changing one line and not altering the `println` statement. Before your change, why did it output `294`? ```java,editable void main() { char a = 'a'; char b = 'b'; char c = 'c'; IO.println(a + b + c); } ``` ## Challenge 5 Without adding any new `println`s, change one line in this program so that it outputs `racecar`. Try to find two ways to do that. ```java,editable void main() { String racecar = "racecar"; int diff = 1; int index = 6; IO.print(racecar.charAt(index)); index += diff; IO.print(racecar.charAt(index)); index += diff; IO.print(racecar.charAt(index)); index += diff; IO.print(racecar.charAt(index)); index += diff; IO.print(racecar.charAt(index)); index += diff; IO.print(racecar.charAt(index)); index += diff; IO.println(racecar.charAt(index)); } ```