"After having a short conversation with them ... there are many times l come up with nothing to say at the end of the conversation." Hideki notes that she will see her coworkers later in the day at times, as in the first two examples below.
Here are the times when Hideki wants to say goodbye:
1 When leaving a coworker in the morning
2 When leaving a coworker in the middle of the day
3 When leaving a coworker as you exit the workplace for the day
Answer: Dear Hideki, I lived in Japan, so I understand why you have this question. In your language, there are specific expressions people always use for such times. In English, though, there are several different things we can say when leaving someone. You guessed at some of them in your email:
You said, "Maybe I should have said, 'Have a good one,' 'Nice talking to you,' or 'Enjoy your time off.'"
你说：“也许我应该说，‘Have a good one（祝你愉快）’，‘Nice talking to you（很高兴跟你聊天）’，或者是‘Enjoy your time off（假期愉快）’”。
Let's look at situation 1: You are leaving a coworker, but you will see him or her at lunch time.
In a school, someone may say to a teacher, "Have a good class," or "See you after class." If you are not speaking to a teacher, you can say, "See you at lunch," "See you a little later," or simply, "Later."
在学校中，人们可以跟老师说：“Have a good class（祝你上课顺利）”或是“See you after class（课后见）”。如果你不是跟老师说话，你可以说：“See you at lunch（午餐见）”、“See you a little later（一会见）”或直接说“Later（稍后见）”。
In situation 2, you had lunch with a coworker and are leaving for the afternoon. Now you can say, "Have a good afternoon." You can also say "Have a good one." That is the same as telling someone to have a good day, afternoon or evening.
在第二种场合中，你跟同事共用午餐后分开。那么你可以说，“Have a good afternoon（祝你下午愉快）”，也可以说“Have a good one（祝你愉快）”。这两句的意思都是祝别人一整天、下午或晚上过得愉快。
Let's look at situation 3, where you are leaving for the evening or weekend. On Fridays, you can always say, "Have a good weekend." On any other workday, you can say, "Good night" or "See you tomorrow."
我们再看第三种场合，你将在晚上或周末前分开。周五的时候你可以说：“Have a good weekend（周末愉快）”。在其他工作日，你可以说：“Good Night（晚安）”或是“See you tomorrow（明天见）”。
There is one more time when you may want to say something. When you leave a meeting, you can say to others, "See you later."
还有一种情况你可能想要说些什么，当你结束会面时可以跟别人说：“See you later（一会见）”。
Your suggestion, "Nice talking to you" is more common when you don't talk to someone every day. If you called a friend, for example, whom you have not seen for months, this would be a good way to close the conversation.
你提到的“Nice talking to you（很高兴跟你聊天）”更常用于跟某人不是每天都交谈的时候。如果你给一位朋友打电话，假设你们几个月没见了，那么这句话就是谈话收尾的一种好办法。
"Enjoy your time off" is something we often say to people who are taking days off from work for vacation. This would not be said every day.
“Enjoy your time off（假期愉快）”这句话我们经常是对那些即将休假的人说的，这不是每天都说的。
And, finally, in any work situation, you can also just say, "Bye!"
And that's ask a teacher!
I'm Jill Robbins. See you later!