Problem 6--(c)

14 December 2001

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

code:
#include
int main(void)
{
int i;
long int s1=0,s2=0;
for(i=1;i<=100;i++)
{
s1+=i*i;
s2+=i;
}
printf("%ld\n",s2*s2-s1);
return 0;
}