$$40 \times 50 \times 60 = 4 \times 5\times 6 \times$$． 
Overseas Competition->Knowledge Point->Calculation Modules->Whole Numbers->Whole Numbers Multiplication and Division
$$4\times10\times5\times10\times6\times10=4\times5\times6\times10\times10\times10=4\times5\times6\times1000$$. 