Chapter 16. PC #8. Sum of Numbers (page 1073) Write a (Java) method that accepts

Question

Chapter 16. PC #8. Sum of Numbers (page 1073)

Write a (Java) method that accepts an integer argument and returns the sum of all the integers from 1 up to the number passed as an argument. For example, if 50 is passed as an argument, the method will return the sum of 1, 2, 3, 4, . . . 50. Use recursion to calculate the sum. Demonstrate the method in a program.

The program should ask the user to enter a number, which is then used to display the sum. if the user enters -1, then exit the program.

Test Case 1

Test Case 2

  5ENTER  10ENTER  -1ENTER  

Explanation / Answer

import java.util.*;

public class Sum{
  
static int calculateSum(int num)
{
int sum;
if(num == 1)
return 1;
else
{ sum = num + calculateSum(num-1);
return sum;
}
}

public static void main(String []args){
System.out.println("Please enter a number");
  
int num,sum;
Scanner s = new Scanner(System.in);
num = s.nextInt();
  
if(num == -1)
{
System.exit(0);
}
  
else
{
sum = calculateSum(10);
System.out.println("Sum of first "+ num + " number is " + sum);
}
}
}

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