Euler_6

Sum square difference

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.

 

Answer:	25164150
Completed on Fri, 11 Jan 2013, 05:58

Go to the thread for problem 6 in the forum.

 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

int func(int n)
{
    int a = n;
    int b = a * n;
    int c = b * n;
    int d = c * n;

    return (3 * d + 2 * c - 3 * b - 2 * a) / 12;
}

int main(int argc, const char *argv[])
{
    printf("%d\n", func(100));

    return 0;
}