While adding and subtracting decimals, students use the relationship between addition and subtraction to find the missing number. They also need to regroup numbers in add and subtract thousandths less than 10 with regrouping worksheet utilizing the relationship between ones, tenth, hundredth, thousandth, etc., To get to the result. 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.