Understanding the Problem
To solve the expression \( \frac{811}{2} \), we need to divide 811 by 2.

Performing the Division
- When you divide 811 by 2, you can visualize it as follows:
- \( 2 \) goes into \( 8 \) four times (since \( 2 \times 4 = 8 \)).
- Subtract \( 8 \) from \( 8 \) leaves \( 0 \).
- Bring down the next digit, which is \( 1 \).
- \( 2 \) goes into \( 1 \) zero times.
- Now, bring down the next digit, which is the last \( 1 \).
- \( 2 \) goes into \( 11 \) five times (since \( 2 \times 5 = 10 \)).
- Subtract \( 10 \) from \( 11 \) leaves \( 1 \).
Therefore, you have a remainder of \( 1 \) after the decimal point.
- The complete calculation shows:
\[
811 \div 2 = 405.5
\]

Finding the Correct Answer
- The question seems to suggest that the answer should be in whole numbers.
- When asked for the nearest whole number or the integer part of \( 405.5 \), you can round down to \( 405 \).
- None of the provided options (4, 3, 81, 9) match \( 405 \).
If instead, we divide \( 8 \) by \( 2 \) (the first digit) and consider how it might relate to the options given, we see that \( 8/2 = 4 \).

Conclusion
Given the original expression and the options provided, the closest answer related to the division of the first digit \( 8 \) by \( 2 \) yields \( 4 \), but it appears that there may have been confusion with the options. Thus, be cautious and double-check the context of the question.