InterviewBit Problems   Large Factorial : Unsolved

About the Large Factorial : Unsolved category (1)
Can some one explain me what's going on (1)
Why the Soulution function being called infinite? (1)
Java Solution using BigInteger - Can we use this approach? (2)
Failing on larger cases, getting partially correct answer (1)
I can't understand why this code gives runtime error above 7 (3)