The next-door neighbor just painted her living room. She says she used two coats of color for coverage, bought four gallons of paint, and had plenty left for touch-ups. Her room is a little smaller, so maybe four cans won’t be enough. Then again, she doesn’t have half a wall of shelves, so maybe four cans is still a good guess.
For better help, ask the employees at the paint store. It’s their business to know which paints need multiple coats and how many square feet each can will cover, so they can tell you how many cans to buy based on your room measurements. When you ask, take time to think about the answer so you learn the simple calculation. In the future, you can do it yourself: multiply the width of a wall by its height to get the square footage of that wall. Do that same calculation for each window (or fireplace) on the wall. Subtract the windows’ values from the wall total. At the paint store, check the labels for the projected square-foot coverage per can and compare it to your requirements. Easy, once you know the formula.
You can sense where I am going with this, can’t you?
While an essay isn’t a math formula, there is a degree of calculation involved in producing one. Remember the five paragraph essay form you learned as a tyke? It has variations designed to support several kinds of writing goals. Using a “formula” to help you create an outline means less time spent wondering what you need to say and more time being creative about saying it.