Ideally, you can calculate the combination of numbers yourself, it’s not hard to do, if you don’t know how to do it, look for tutorials on the internet. But if you need to do it very quickly, then, of course, you can use such a tool as an online calculator, so you don’t have to spend time calculating in your mind. And I can tell you that there are a lot of such tools on the Internet, for example, here is a great combination calculator https://www.calculator.io/combinations-calculator/ .