Project Euler question 6 is:

The sum of the squares of the first ten natural numbers is,

12 + 22 + … + 102 = 385

The square of the sum of the first ten natural numbers is,

(1 + 2 + … + 10)2 = 552 = 3025

Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 − 385 = 2640.

Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.

My solution in Java:

public class Euler6
{
    private long sumOfSquares()
    {
        long total = 0;
        for ( int i = 1; i < 101; i++)
        {
            total += i*i;
        }

        return total;
    }

    private long squareOfSums()
    {
        long total = 0;
        for ( int i = 1; i < 101; i++ )
        {
            total += i;
        }
        return total*total;
    }

    public long answer()
    {
        return squareOfSums() - sumOfSquares();
    }
}