Took me a few seconds to parse the question (that it was about "35 factorial" and not about some binary representation of "35" ended with interrobang "?!") One

Took me a few seconds to parse the question (that it was about "35 factorial" and not about some binary representation of "35" ended with interrobang "?!") One possible solution in Python: import operator fact = str(reduce(operator.mul, xrange(2,36))) print len(fact) - len(fact.rstrip('0')) >>> 8 Please forgive me for using strings for numerical operation, it was for a brevity's sake (I still remember Leah Culver getting chastised here on HN).