Students convert among fractions, terminating decimals, and percents, simplify equivalent forms, and compare or order positive and negative rational numbers, including zero, using signs, common units, and number-line reasoning. Students add, subtract, multiply, and divide numerical fractions, mixed numbers, decimals, and signed fractional quantities, interpreting operations, simplifying results, estimating, and recognizing that division by zero is undefined. Students evaluate numerical expressions involving rational numbers by applying grouping symbols, whole-number exponents, and the order of multiplication or division before addition or subtraction, while preserving equivalent values and signs.