Java

3) Use recursion to add all of the numbers between 5 to 10.

public class Recursion2 { public static void main(String[] args) { int result = sum(5, 10); System.out.println(result); } public static int sum(int start, int end) { if (end > start) { return end + sum(start, end - 1); } else { return end; } } }

4) Use recursion to add all of the numbers up to 10.

• When the sum() function is called, it adds parameter k to the sum of all numbers smaller than k and returns the result. When k becomes 0, the function just returns 0. When running, the program follows these steps:
• 10 + sum(9) 10 + ( 9 + sum(8) ) 10 + ( 9 + ( 8 + sum(7) ) ) ... 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 + sum(0) 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 + 0

public class Recursion1 { public static void main(String[] args) { int res = sum(10); System.out.println(res); } public static int sum(int k) { if (k > 0) { return k + sum(k - 1); } else { return 0; } } }