This worksheet invites students to add and subtract hundredths and thousandths less than 10, which helps them become proficient in addition and subtraction. To ensure that each decimal has the same number of digits while adding or subtracting decimals, students align the decimal points and insert additional zeros to the right of the number. Students then add or subtract digits at each place to find the answer. This worksheet is about practicing with the horizontal format in which numbers are written side by side. To develop flexibility with numbers and operations, students need to have enough practice in this format and not just rely on the vertical/column method.