Many people in our society believe that math has little to do with graphic design, those people are wrong. Math is used continually in graphic design whether it is noticed or not. Coordinate systems should be used when doing layout for any type of project. It is one of the most often ignored things a graphic designer can do. Getting things to line up or to be an accurate size for trimming have never been easier than with a computer and modern programs. All of the programs used in graphic design have a transform palette for a reason, that reason is to make our lives easier and to make everything line up and fit perfectly and it wouldn’t line up without math.
Most common designers never work with larger spreads then magazines. When working in large format, your art board may not be big enough for your drawing or your print vendor may tell you to work in 1:10 scale for a certain image resolution. Sometimes it's easier if everything for a project is done in 1/2 or 1/4 scale. If you can't do that kind of simple math then do not work in large format.
Math is also used when calculating your image resolution, the more pixels in the resolution the better the quality of the image will be. If you have a client who is asking you on the phone if a photo is any good, you can do the math or open Photoshop real quick and use the New File box. But you have to know where to put your numbers and what your numbers mean. Another important math aspect is accounting. You have to bill your clients and pay your taxes.
The most important use of math in graphic design is being able to ask your print vendor how many days he needs to print something for you, then being able to subtract that number from your actual due date to come up with your file submission date. Math could be used in a variety of ways such as learning new perspectives on symmetry and geometry. Some examples of how math is used is Squaring, resolution, dimensions, product labeling, decals, wraps, geometry for sign...