Students use the relationship between addition and subtraction to find the missing number while adding decimals. To reach the answer, they must also regroup the numbers in add thousandths less than 100 with regrouping worksheet using the relationships between ones, tenths, hundredths, thousandths, etc. 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.