This C program calculates the factorial of a user-input number. It includes header files for input/output and console functions. The main function prompts the user for a number, calls the factorial function to calculate the result, and prints the number and its factorial. The factorial function initializes the factorial to 1, uses a for loop to multiply it by integers from 1 to the input value, and returns the final factorial.

1. #include<stdio.h>
#include<conio.h>
unsigned long int factorial (unsigned char v);
int main(void)
{
unsigned int n;
unsignedlongint resultado;
printf("nescriba un numero");
scanf("%i",&n);
resultado=factorial(n);
printf("n nel factorial de (%i)=%i",n,resultado);
getch();
return 0;
}
unsigned long int factorial (unsigned char v)
{
unsigned long int f=1;
unsigned char i;

2. for (i=1;i<=v;i++)
f=f*i;
return (f);
}