4470 copies. Sort out 745 books a day, that is, sort out 745 books six times in six days, so you can sort out 4470 books in six days. Multiplication is a shortcut to add up the same numbers. The result of its operation is called product. From the philosophical point of view, multiplication is the result of qualitative change caused by additive quantity. The multiplication of integer, rational number and real number is a systematic summary of this basic definition.