Final answer:
When adding or subtracting decimal numbers, align the decimals to match the place values and then round the result to the same number of decimal places as the least precise number in the original set.
Step-by-step explanation:
The process of adding and subtracting decimal numbers involves two key steps. The first step is to align the decimals vertically so that the same place values are lined up in each column. This means the ones, tenths, hundredths, etc., should be directly above or below each other for each number you are working with. The second step, after performing the addition or subtraction calculation, is to round the result to the same number of decimal places as the number with the least decimal places. This ensures that the precision of the answer is not greater than the least precise number in the original problem.
For example, if you are asked to subtract 6.23 from 10.859, you would align the decimals to get:
10.859
- 6.230
___________
After subtraction, you would get 4.629, which you then round to 4.63 because the second number, 6.23, has two decimal places, which is the least in this case.