To determine which of the given numbers is rounded to three significant figures, we first need to understand what significant figures are. Significant figures are the digits in a number that contribute to its precision. This includes all non-zero digits, any zeros between significant digits, and any trailing zeros in the decimal portion. ### Step-by-Step Explanation 1. **Identify Significant Figures**: - **Option A: 0.004567** - The leading zeros (0.00) are not significant. The significant figures start from the first non-zero digit, which is 4. Thus, the significant figures are 4, 5, 6, and 7. This number has **4 significant figures**. - **Option B: 123.456** - All digits are non-zero, so all are significant. The significant figures are 1, 2, 3, 4, 5, and 6. This number has **6 significant figures**. - **Option C: 5.6789** - All digits are non-zero, so all are significant. The significant figures are 5, 6, 7, 8, and 9. This number has **5 significant figures**. - **Option D: 0.000789** - The leading zeros (0.000) are not significant. The significant figures start from the first non-zero digit, which is 7. Thus, the significant figures are 7, 8, and 9. This number has **3 significant figures**. 2. **Determine Which Option is Rounded to Three Significant Figures**: - From the analysis above, **Option D: 0.000789** is the only number that has exactly **3 significant figures** (7, 8, and 9). ### Why Other Options Are Incorrect - **Option A: 0.004567** has 4 significant figures, not 3. - **Option B: 123.456** has 6 significant figures, not 3. - **Option C: 5.6789** has 5 significant figures, not 3. ### Summary of Key Points - **Significant Figures**: Digits that contribute to the precision of a number, including all non-zero digits and zeros between them. - **Leading Zeros**: Do not count as significant figures. - **Trailing Zeros**: Count as significant only if they are to the right of a decimal point and follow a non-zero digit. ### Revision Summary - Significant figures include all non-zero digits and zeros between them. - Leading zeros are not counted as significant figures. - The only option with exactly three significant figures is **D: 0.000789**. - Always count significant figures carefully, especially in decimal numbers.