Every one of us can remember being in school and asking our teachers (no matter what class it was), "When are we going to use this in the real world?" And your teacher probably didn't have a very good answer. It was probably something along the lines of, "You won't, but you should learn it anyway." Additionally, when politicians and other people debate what we need to be teaching in schools, a lot of the ideas about what is necessary and what is not come down to what application these things can have in "the real world." To me, though, there are two problems with this line of thinking.
The first is the very idea of "the real world" as distinct from the world of education. Maybe this is because much of what you learn in school becomes applicable to other classes (e.g., science classes require a certain background in math), but doesn't ever seem to have application in the everyday life. Or, one can't imagine what sort of a job this kind of information would require. The fact of the matter, though, is that all of us are going to end up with different kinds of jobs when we leave school. Some of them will involve a lot of math and science. Some of them will involve a lot of writing.
And this brings me to the more important problem of "when will we need this": you are missing the point of education. If you are going to learn exactly what you need for a particular job, you go to a technical school. But the point of a broad education is to give you a perspective on the world that you wouldn't otherwise have. Our modern world is a vast, complicated place. Having a basic understanding of each of the components of the world helps us to understand why things are the way they are, and why things work the way they do. As one example, if you are going to give two shits about politics—and you should—you ought to know some things about world history, and the history of your own country. (Hell, just about anything you need to know about politics is in fuckin' Thucydides. He wrote a book that he wanted to endure across the ages, and he damn well succeeded.) Additionally, our current political debates about climate change, teaching evolution in schools, come about from a willful rejection of established science.
So, you won't ever need this in the real world, but at the same time, you will always need this in the real world, everywhere. If you understand why this answer makes sense, then you'll understand why it's such a dumb question in the first place.