Example: Sum of Squares using Formula in C

C
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// Sum of Squares using Formula
#include <stdio.h>

int main() {
    int n;
    long long sum_of_squares = 0; // Use long long for the sum

    // Step 1: Prompt user for input
    printf("Enter a positive integer (n): ");

    // Step 2: Read the value of n
    if (scanf("%d", &n) != 1 || n < 1) {
        printf("Invalid input. Please enter a positive integer.\n");
        return 1; // Indicate an error
    }

    // Step 3: Apply the formula
    // (long long)n is used to ensure the multiplication is done using long long arithmetic
    // to prevent intermediate overflow before division.
    sum_of_squares = (long long)n * (n + 1) * (2 * n + 1) / 6;

    // Step 4: Print the result
    printf("The sum of squares up to %d is: %lld\n", n, sum_of_squares);

    return 0;
}