Looking at that issue from a (mathematical) function perspective, this is a shared need across mathematics, computer science, physics, and so on: they all want to know how expensive a function is. This is why a common notation was invented by Edmund Landau: the Big O notation (or Landau notation) consisting of the uppercase letter O, which declares the order of a function. The main growth factor is then put into parentheses following the letter O.
There are other, related notations that use small o, Omegas, Theta, and others, but those are less relevant in practical terms. Check the Further reading section for an article by Donald Knuth on this.
