## Project Euler 006 – C#

8 03 2011

Problem 6

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.

Solution

//The sum of the squares of

//the first ten natural numbers is,

//1^2 + 2^2 + … + 10^2 = 385

//The square of the sum of the

//first ten natural numbers is,

//(1 + 2 + … + 10)^2 = 55^2 = 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.

namespace ProjectEulerCSharp_006

{

class Program

{

static void Main(string[] args)

{

int sumsqrs = 0;

int sqrsums = 0;

for (int i = 0; i <= 100; i++)

{

sumsqrs += i * i;

sqrsums += i;

}

sqrsums *= sqrsums;

System.Console.WriteLine(sqrsums – sumsqrs);

}

}

}

Discussion

No trick today.