Question

What will be the number of significant figures in the sum of \( 2.34,\; 12.1,\; \text{and } 0.056 \)?

• A. 2
• B. 3
• C. 4
• D. 5

Hint:

For addition and subtraction, rounding is done based on decimal places, not directly on significant figures.

Answer 1

The Correct Option is B

To determine the number of significant figures in the sum of \( 2.34, 12.1, \) and \( 0.056 \), we need to understand the rules of significant figures in addition.

1. First, let's add the numbers: \( 2.34 + 12.1 + 0.056 \). 

2.34

12.1

+ 0.056

----

14.496

1. The rule for significant figures in addition and subtraction is that the result should have the same number of decimal places as the term with the least number of decimal places.
2. Here, \( 2.34 \) has two decimal places, \( 12.1 \) has one decimal place, and \( 0.056 \) has three decimal places. Thus, the term with the least number of decimal places is \( 12.1 \), which has one decimal place.
3. Therefore, we have to round our result \( 14.496 \) to one decimal place. Rounding \( 14.496 \) to one decimal place gives us \( 14.5 \).
4. The number \( 14.5 \) has three significant figures.

Hence, the number of significant figures in the sum is 3.