Rule 3. In adding or subtracting, the least significant digit(最小的有效数字) of the sum or difference occupies the same relative position as the least significant digit of the quantities being added or subtracted. In this case the number of significant figures is not important; it is the position that matters Example 1039kg+210kg+0319kg=106319k9=1063kgRule 3. In adding or subtracting, the least significant digit (最小的有效数字)of the sum or difference occupies the same relative position as the least significant digit of the quantities being added or subtracted. In this case the number of significant figures is not important; it is the position that matters. Example: 103.9kg+2.10kg+0.319kg=106.319kg=106.3kg