Math.pow(i,2)
accepts doubles as parameters. Doubles are not 100% precise,
you lose precision. Stick to operations on int/long only. The answer is pretty small
and fits even into an int.
Not sure why you use 100000 as your limit, problem 6 has 100 as a limit.
In Java when results of integer arithmetic don't fit into int variables,
you should use long, when they don't fit even into long variables, you
should use BigInteger.
But avoid doubles, they are not precise for such kinds of tasks.
Here is your program corrected.
import java.math.BigInteger;
public class Problem_Six {
public static void main(String[] args) {
BigInteger sum = BigInteger.ZERO;
BigInteger sumSqr = BigInteger.ZERO;
BigInteger sumOfSqr = BigInteger.ZERO;
for (long i = 1; i <= 100000; i++) {
sum = sum.add(BigInteger.valueOf(i));
sumOfSqr = sumOfSqr.add(BigInteger.valueOf(i * i));
}
sumSqr = sum.multiply(sum);
System.out.println(sumSqr + " " + sumOfSqr);
System.out.println(sumSqr.subtract(sumOfSqr).toString());
// System.out.println(Long.MAX_VALUE);
}
}