Final answer:
In addition and subtraction problems in mathematics, the answer should be rounded to match the least precise measurement involved. Proper units and significant figures must also be included in the answer. Extra precision can be used in the calculation for checking but should not be reported in the final result.
Step-by-step explanation:
When dealing with mathematical problems that involve the addition or subtraction of measured values, it's essential to express your answers with the correct number of significant figures and proper units. The final answer for such calculations should mirror the precision of the least precise measurement in the set. This means if you are adding or subtracting numbers, you need to round the result to the same number of decimal places as the number with the fewest decimal places. This practice ensures the accuracy of the reported result does not exceed the precision of the initial measurements.
For example, if you are adding 3.12 (measured to the nearest hundredth) and 4.1 (measured to the nearest tenth), the result should be expressed to the nearest tenth, as 4.1 is the least precise measurement. Similarly, when subtracting inexact numbers like 180 (two significant figures), 16 (two significant figures), and 2.20 (three significant figures), the answer should have two significant figures, aligning with the smallest number of significant figures among the measured values.
It is also a good practice to add one more decimal place to your answer during the calculation phase to check that the rounding is correct, but the final answer should still reflect the least precise measurement. Remember to include proper units to give context to your numerical results, as they are a vital part of scientific and mathematical communication.