If a measured quantity has 'n' significasnt figures, the reliable digits in it are

Options

A. n
B. n - 1
C. 2n
D. n/2

Answer

To solve the question regarding the reliable digits in a measured quantity with 'n' significant figures, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Significant Figures**:
- 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 trailing zeros in the decimal part.

2. **Identifying Reliable Digits**:
- In any measured value, the last digit is often considered less reliable. This is because it may be subject to rounding or measurement error.

3. **Example for Clarity**:
- Consider a measured value such as 1.25694.
- Here, the number has 6 significant figures (1, 2, 5, 6, 9, and 4).
- However, the last digit (4) is not fully reliable because it may have been rounded.

4. **Calculating Reliable Digits**:
- Since the last digit is uncertain, we can conclude that the reliable digits in this case are the first five digits (1.2569).
- Therefore, the reliable digits can be calculated as:
\[ \text{Reliable Digits} = n - 1 \]
- If 'n' is the total number of significant figures, then the reliable digits would be \( n - 1 \).

5. **Conclusion**:
- Thus, if a measured quantity has 'n' significant figures, the reliable digits in it are \( n - 1 \).

### Final Answer:
The reliable digits in a measured quantity with 'n' significant figures are \( n - 1 \).

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