3. (D) Write a program to find the factorial of a number.

3. (D) Write a program to find the factorial of a number.

#include <stdio.h>
	int main()
	{
	int n, i;
	unsigned long long factorial = 1;
	printf("Enter an integer: ");
	scanf("%d",&n);
	// show error if the user enters a negative integer
	if (n < 0)
	printf("Error! Factorial of a negative number doesn't exist.");
	else
	{
	for(i=1; i<=n; ++i)
	{
	factorial *= i; // factorial = factorial*i;
	}
	printf("Factorial of %d = %llu", n, factorial);
	}
	return 0;
	}