You are correct in pointing out that when reporting results, the number of significant figures (sig figs) is important. The rule of thumb is that the final answer should be reported with the same number of significant figures as the least precise number in the calculation.

In this case, if 18 is part of a calculation, it has 2 significant figures. Thus, the result of any mathematical operation involving this number should generally be rounded to 2 significant figures as well, provided it's the least precise number in the calculation.

Would you like further details on this topic or the specific context of your question?

Here are 5 related questions to deepen understanding:

1. How do you determine the number of significant figures in a number?
2. What is the rule for significant figures when multiplying or dividing?
3. How do significant figures work when adding or subtracting numbers?
4. What role do leading and trailing zeros play in determining significant figures?
5. Can you explain how rounding affects significant figures in real-world measurements?

Tip: When performing calculations, always identify the number with the fewest significant figures first, as it will dictate how you round your final answer.