Actually Applicable Application Problems and Brainteasers/Materials for Projects: Yarn for Flat Projects

Overview
Knowing how much yarn is needed to complete a project is important if you are making something for your own use or as a gift, to make sure you buy enough yarn, and if you are making the items to sell, to make sure you are charging enough considering the cost of materials.

General Method

 * 1) Make a swatch.
 * 2) * Usually this will be rectangular but it can vary depending on the project.
 * 3) Use a high-enough precision scale to weigh the swatch.
 * 4) Calculate the swatch's area.
 * 5) Divide the swatch's weight by its area to find the weight of yarn needed to make each square inch.
 * 6) Multiply the weight of yarn per square inch by the number of square inches in the project to find the total weight of yarn needed for the project.
 * 7) If necessary, do a unit conversion to get the amount of yarn into a convenient unit.

Problems
How much yarn would you need to make a scarf 10 inches wide and 4 feet long?

Make Your Own Problem
Pick a project you would like to make, and figure out how much yarn you need for it.