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

Step 1: Perform the addition.
\[ 2.34 + 12.1 + 0.056 = 14.496. \]
Step 2: Apply the rule for addition of significant figures.
In addition, the result should be rounded off to the least number of decimal places among the given numbers.
Here: \[ 2.34 \rightarrow 2 \text{ decimal places}, \quad 12.1 \rightarrow 1 \text{ decimal place}, \quad 0.056 \rightarrow 3 \text{ decimal places}. \] The least number of decimal places is 1.
Step 3: Round the result accordingly.
\[ 14.496 \approx 14.5 \quad (\text{rounded to 1 decimal place}). \]
Step 4: Count significant figures in the final answer.
\[ 14.5 \text{ has } 3 \text{ significant figures}. \]