Let's solve the problem step-by-step and ensure the final answer is expressed with the correct number of significant figures:
1. Initial Addition:
- First, we add the numbers: [tex]\(2.13 + 1 = 3.13\)[/tex].
2. Determining Significant Figures:
- The number of significant figures in a result should follow the least number of significant figures among the input numbers.
- Here, [tex]\(2.13\)[/tex] contains three significant figures, and [tex]\(1\)[/tex] contains one significant figure.
3. Applying Significant Figures Rule:
- Since [tex]\(1\)[/tex] has only one significant figure, the result should be rounded to one significant figure.
4. Rounding the Result:
- The number [tex]\(3.13\)[/tex] rounded to one significant figure is [tex]\(3\)[/tex].
Thus, the correct answer, expressed to the correct number of significant figures, is [tex]\(\boxed{3}\)[/tex].