Here’s a simple factorial program in C:

```
#include <stdio.h>
int main()
{
int num, i, fact=1;
printf("Enter a number: ");
scanf("%d", &num);
for(i=1; i<=num; i++)
{
fact = fact * i;
}
printf("Factorial of %d is %d", num, fact);
return 0;
}
```

In this program, we first declare the variables `num`

, `i`

, and `fact`

, where `num`

is the number for which we want to find the factorial, `i`

is a loop variable, and `fact`

is the variable that will hold the factorial value.

We then prompt the user to enter a number using the `printf()`

function and read the input using the `scanf()`

function.

Next, we use a `for`

loop to calculate the factorial of the entered number. The loop runs from 1 to `num`

and multiplies the value of `fact`

by the loop variable `i`

in each iteration. This results in the factorial of `num`

being stored in `fact`

at the end of the loop.

Finally, we print the factorial of the entered number using the `printf()`

function.

Note that this program assumes that the entered number is a positive integer. If a negative number or a decimal value is entered, the program may not work correctly.