The Problem:

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):

// Author: William Clausen // // Date: Jan 7, 2013 // // This program solves Problem 6 form Project Euler. /* Problem Statement: * Find the difference between the sum of the squares of the first one hundred * natural numbers and the square of the sum. */ import java.lang.Math; // For squaring numbers public class Problem6 { // Data members to store the number of natural numbers to use, // the sum of the squares and the square of the sum. public int sumSquare; public int squareSum; public int Num; Problem6(int num) { Num = num; sumSquare = 0; squareSum = 0; } // Method that solves the problem and returns the result. // The heavy lifting is done in the two helper functions, // sumSquares(int) and squaredSum(int). public int solve() { sumSquare = sumSquares(Num); squareSum = squaredSum(Num); return squareSum - sumSquare; } // This function computes the sum of the squares of the natural numbers // from 1 to num. private int sumSquares(int num) { int sum = 0; for (int i = 1; i <= num; i++) { sum += (int) Math.pow(i,2); } return sum; } // This function computes and returns the square of the sum of the natural // numbers from 1 to num. private int squaredSum(int num) { int totalSum = (num)*(num+1); totalSum = totalSum/2; totalSum = (int) Math.pow(totalSum, 2); return totalSum; } } // Solution: 25164150

Straightforward problem. As always, I love feedback on how this solution could be improved!