Each person has approximately 80,000 to 125,000 hairs. The safe posterior occipital donor area occupies about a quarter of the scalp. Taking the maximum half of the safe area that can be used, it is about 10,000 hairs. Therefore, if 3,000 hairs are transplanted each time, only 3 times are possible. Of course, it is possible to do the fourth or the fifth hair transplants after 3 surgeries, but the number of hair transplanted each time needs to be carefully considered.