diff --git a/fact.c b/fact.c
new file mode 100644
index 0000000..97ad01c
--- /dev/null
+++ b/fact.c
@@ -0,0 +1,20 @@
+#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;
+}