What is the largest number which is both less than $$2\times3\times5\times7$$ and also a divisor of $$2 \times 3 \times 5\times 7$$? 
Overseas Competition->Knowledge Point->Calculation Modules->Whole Numbers->Whole Numbers Multiplication and Division
The largest divisor of $$2\times3\times5\times7$$ that is less than~ is $$3\times5\times7$$, which we get by dropping the smallest factor. 