In one sentence, describe what the following article is about:

Though linoleum and vinyl flooring are fairly cheap compared to flooring options like hardwood and tile, you still won't want to spend any more money on your flooring project than necessary. Figuring out how much linoleum your project calls for beforehand can prevent you from wasting money on excessive flooring material and save you the hassle of having to run back to the hardware store if you don't have enough. For most projects, the easiest way to do this is simply to use an online calculator. Though online calculators will vary, most (including the one above) simply require you to input the length and width of your floor section (or sections) to receive a total estimate. For floor sections that are square or rectangular, you'll only need one length and width, but for a differently-shaped area of floor, you'll need to divide your square into rectangular sections and find a length and width for each to get an accurate total. You don't need to use a calculator to figure out how much linoleum you need — it's also pretty easy to find this amount by hand. Use one of the equations below to determine exactly how much linoleum is necessary for your project depending on whether you're buying sheet linoleum by the yard or tiled linoleum. Keep in mind that, regardless of the equation you use, your floor area value will be the length of your floor times its width (for each rectangular section of floor).  For sheet linoleum: (Floor area)/9 = # of Square yards of linoleum needed For 9-inch tiles: (Floor area)/0.5626 = # of 9-inch linoleum tiles needed For 12-inch tiles: (Floor area) = # of 12-inch linoleum tiles needed As with all home improvement projects, it's a smart use of your time to buy just a little extra when you're shopping for linoleum flooring. Just as you might buy extra concrete when pouring a new driveway, buying extra linoleum gives you the ability to correct for small mistakes you might make and also accounts for minor errors you may have made during the process of calculating the amount of linoleum you need. In addition, extra linoleum can be stored almost indefinitely and used to patch minor damage to your floor, line the bottom of cabinets under your sink, and for a variety of other home-improvement projects.

Summary:
Use an online calculator. Calculate your amount by hand. Buy a little bit more than you think you need.