U.S. National Standards
N.1. Number and Operations (NCTM)
1.1. Understand numbers, ways of representing numbers, relationships among numbers, and number systems.
1.1.1. Work flexibly with fractions, decimals, and percents to solve problems.
1.1.4. Understand and use ratios and proportions to represent quantitative relationships.
1.3. Compute fluently and make reasonable estimates.
1.3.4. Develop, analyze, and explain methods for solving problems involving proportions, such as scaling and finding equivalent ratios.