Final answer:
The number of significant digits in the final answer depends on the least precise measured value. For multiplication and division, the final answer can have no more significant figures than the least precise value, while for addition and subtraction, the final answer cannot have more decimal places than the least precise value.
Step-by-step explanation:
When combining measurements with different degrees of accuracy and precision, the number of significant digits in the final answer can be no greater than the number of significant digits in the least precise measured value. There are two different rules, one for multiplication and division and the other for addition and subtraction.
For multiplication and division, the final answer can have only as many significant figures as the least precise value. For example, if you are multiplying 2.3 (2 significant figures) by 4.567 (4 significant figures), the final answer can contain only 2 significant figures.
For addition and subtraction, the final answer cannot have more decimal places than the least precise value. For example, if you are adding 12.345 (3 decimal places) to 6.7 (1 decimal place), the final answer should only have 1 decimal place.