Hi Yes it prints n! and is pretty good at doing that(large precision) I commented out the #include<stdio.h> and ran the preprocessor on the original file. Then i ran indent on the result to give it a decent look. Then i changed all the variables to more meaningful ones. The thirteenth line looks something like this

for (l = 0; l < 14; putchar ("\t"8)>l"9!.)>vl"[l] ^ 'L'), ++l);

It is supposed to print something like "Enter number: " The perplexing part is the putchar() in the loop Taking a close look at it you can see that he has a 14 character striing in the quotes "\t"8)>l"9!.)>vl" .This he indexes by [l]. While the loop executes he extracts each character systematically and does an bitwise exclusive OR with 'L' and prints the resulting character.This prints the string. Now the question why does he do an XOR with 'L' is easy. He could have done an XOR with nethin for the matter but then the string in quotes would have been different. If a XOR b = c then a XOR c = b This explains the 13th line. Will try to make sense out of the remaining code.