10101010

D

The binary number 10101010 can be converted to its decimal equivalent by adding up the values of each digit in the binary number, multiplied by their corresponding power of 2.

Starting from the rightmost digit, the powers of 2 increase by 1 for each digit moving to the left. Thus, the rightmost digit has a power of 2^0 (which equals 1), the next digit to the left has a power of 2^1 (which equals 2), and so on.

So for the binary number 10101010, we have:

Copy code
1 * 2^7 + 0 * 2^6 + 1 * 2^5 + 0 * 2^4 + 1 * 2^3 + 0 * 2^2 + 1 * 2^1 + 0 * 2^0 

which simplifies to:

Copy code
128 + 0 + 32 + 0 + 8 + 0 + 2 + 0 

and then to:

Copy code
170 

Therefore, the decimal equivalent of the binary number 10101010 is 170. Hence the answer is D.