Question

Write the program in Java to find the sum of the following series:

S = 2 − 4 + 6 − 8 + ................. to n 

Answer 1

import java.util.*;
public class Q2b
{ public static void main(String args[])
{ int sum = 0, n;
Scanner obj = new Scanner(System.in);
System.out.printn("Enter the number of terms...n");
n = obj.nextInt();
for (int i = 2; i <= (2 * n); i = i + 2) // 2n because the each term is a multiple of 2
{ if (i % 4 == 0)
sum = sum - i; 
else
sum = sum + i;
}
System.out.println("Sum of the series = " + sum);
}}