If the immediate insignificant digit to be dropped is 5 then there will be two different cases
(A If the preceding digit is even , it is to be unchanged and 5 is dropped.
(B) If the preceding digit is odd, it is to be raised by 1,

Options

A. Only A is correct
B. A, B are correct
C. Only B is correct
D. A, B are wrong

Answer

To solve the problem regarding rounding off numbers when the immediate insignificant digit is 5, we will consider the two cases mentioned in the question.

### Step-by-Step Solution:

1. **Understanding the Problem**: We need to round off numbers that have a significant digit of 5. There are two cases to consider based on the preceding digit (the digit immediately before the 5).

2. **Case A - Preceding Digit is Even**:
- If the digit before the 5 is even, we simply drop the 5 without changing the preceding digit.
- **Example**: Consider the number 4.565. The digit before 5 is 6 (which is even). Therefore, when we round off, we keep 6 unchanged and drop the 5.
- Result: 4.56

3. **Case B - Preceding Digit is Odd**:
- If the digit before the 5 is odd, we increase the preceding digit by 1 and drop the 5.
- **Example**: Consider the number 4.135. The digit before 5 is 3 (which is odd). Therefore, we increase 3 by 1 and drop the 5.
- Result: 4.14

4. **Additional Examples**:
- For the number 4.525, the digit before the 5 is 2 (even), so we drop the 5.
- Result: 4.52
- For the number 4.145, the digit before the 5 is 4 (even), so we drop the 5.
- Result: 4.14

5. **Conclusion**:
- In summary, if the preceding digit is even, we drop the 5 without changing it, and if the preceding digit is odd, we increase it by 1 and drop the 5. Both cases are valid and correct.