That depends how you define a tense. In German there aren't many. Why don't you buy a grammar book to find out? Thing is, there are only three tenses: present and past and imperfect. The rest are all aspects of these two. But others beg to differ and insist there are future tenses (two of them in fact) and conditionals, not to mention the subjunctives and all that. So for learning purposes, you would need to learn quite a few verb transformations. Best go online or get a good book to find them