Students classify real numbers as natural, whole, integer, rational, or irrational, distinguish rational and irrational values, and represent, compare, and order positive and negative numbers, zero, fractions, decimals, and radicals on a number line. They evaluate square roots of nonnegative perfect squares, simplify square roots by extracting perfect-square factors, and estimate irrational square roots between rational benchmarks to the tenths or hundredths. They add and subtract like square radicals after simplifying them, combining coefficients while recognizing that unlike radicals cannot be combined.