The ones digit of $$9\times 8\times 7\times 6\times 5\times 4\times 3\times 3\times 4\times 5\times 6\times 7\times 8\times 9$$ is． 
Overseas Competition->Knowledge Point->Number Theory Modules->Place Value and Number Bases->Numbers
Since $$5\times 4 = 20$$, the ones digit of the given product must be $$0$$. 