What is coworker gave me his number?

As an AI language model, I cannot know why your coworker gave you his number but can provide you general information about it. If you are interested in building a working relationship or want to discuss any work-related matters, having your coworker's number can prove valuable. It allows you to contact them easily and quickly. Additionally, having the number of a coworker can help you stay connected and informed about any developments in the workplace. It can also be useful for networking and making professional connections. However, it is important to respect coworker's privacy and only contact them outside of work hours if it is necessary.