Answer :

To determine the largest decimal number that can be represented with eight bits, let's understand how binary numbers work.

1. Understand the concept of bits: Each bit in binary represents an exponent of 2, starting from [tex]\(2^0\)[/tex] for the rightmost bit and increasing by powers of 2 as you move to the left. An 8-bit number uses eight binary digits, from [tex]\(b_7 b_6 b_5 b_4 b_3 b_2 b_1 b_0\)[/tex].

2. All bits set to 1: To find the maximum value, all eight bits should be set to 1. This would look like:
[tex]\[ 11111111_2 \][/tex]
This binary number needs to be converted to its decimal equivalent.

3. Calculate the decimal equivalent: Begin by expanding the binary number in terms of powers of 2:
[tex]\[ 1 \times 2^7 + 1 \times 2^6 + 1 \times 2^5 + 1 \times 2^4 + 1 \times 2^3 + 1 \times 2^2 + 1 \times 2^1 + 1 \times 2^0 \][/tex]
Calculating each term:
[tex]\[ 1 \times 128 + 1 \times 64 + 1 \times 32 + 1 \times 16 + 1 \times 8 + 1 \times 4 + 1 \times 2 + 1 \times 1 \][/tex]
Which simplifies to:
[tex]\[ 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 \][/tex]

4. Sum the values:
[tex]\[ 128 + 64 = 192 \][/tex]
[tex]\[ 192 + 32 = 224 \][/tex]
[tex]\[ 224 + 16 = 240 \][/tex]
[tex]\[ 240 + 8 = 248 \][/tex]
[tex]\[ 248 + 4 = 252 \][/tex]
[tex]\[ 252 + 2 = 254 \][/tex]
[tex]\[ 254 + 1 = 255 \][/tex]

Therefore, the largest decimal number that can be represented with eight bits is [tex]\( \boxed{255} \)[/tex].

Given the multiple-choice options:
a. 512
b. 255
c. 128
d. 256

The correct answer is [tex]\( \boxed{255} \)[/tex].