A can of paint will cover 400 square feet. What is the length of the edge of the largest square that can be painted with this can of paint?

One gallon can of paint will cover up to 400 square feet, which is enough to cover a small room like a bathroom. Two gallon cans of paint cover up to 800 square feet, which is enough to cover an average size room. This is the most common amount needed, especially when considering second coat coverage.