Read, write, identify, and expand nonnegative decimals through the thousandths place, including tenths, hundredths, thousandths, zero placeholders, equivalent trailing-zero forms, and conversions between decimals and fractions with denominators of 10, 100, or 1,000. Compare, order, and round decimals through the thousandths place, and add or subtract them by aligning place values, inserting equivalent zeros, and regrouping as needed. Solve contextual problems involving decimals through the thousandths place by selecting appropriate addition, subtraction, multiplication, or division, representing quantities with equations or models, and checking results through estimation and place-value reasoning.