Below is an instruction that describes a task. Write a response that appropriately completes the request in Chinese. Please answer in Chinese.

### Instruction:
 扎克去过的国家数量是帕特里克去过的国家数量的两倍。帕特里克去过的国家数量是约瑟夫去过的国家数量的三倍。约瑟夫去过的国家数量是乔治去过的国家数量的一半。如果乔治去过6个国家，那么扎克去过多少个国家？


### Response:
 约瑟夫去过6 / 2 = <<6/2=3>>3个国家。
帕特里克去过3 * 3 = <<3*3=9>>9个国家。
所以，扎克去过2 * 9 = <<2*9=18>>18个国家。