We can talk about those things without the language of calculus, though: "this graph shows requests per second, and that graph shows cumulative requests." And I

We can talk about those things without the language of calculus, though: "this graph shows requests per second, and that graph shows cumulative requests." And I think it should be clear how to derive one graph from the other, with or without calculus training. IMX numerical integration is useful in some areas (like physics simulations), but I haven't encountered any non-trivial applications of the kind of calculus that's taught in most schools, which focuses on continuous functions over the reals.