Which of the following measurements is correctly reported to the appropriate number of significant figures after adding 12.34 g and 0.567 g?

• A. 12.9 g
• B. 13.0 g
• C. 12.91 g
• D. 12.907 g

Answer: (A)

Verified step by step guidance

1. Identify the number of decimal places in each measurement: 12.34 g has 2 decimal places, and 0.567 g has 3 decimal places.
2. When adding or subtracting, the result should be reported with the same number of decimal places as the measurement with the fewest decimal places. Here, that is 2 decimal places.
3. Add the two numbers: 12.34 g + 0.567 g = 12.907 g (exact sum before rounding).
4. Round the sum to 2 decimal places (because 12.34 g has only 2 decimal places), which means keeping digits up to the hundredths place.
5. Compare the rounded result to the given options and select the one that matches the correctly rounded value.