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Explanation:
Check out the table below. Each 1 and 0 corresponds to a power of 2. A 1 indicates that we'll add on that power of 2 while a 0 means we ignore it. We will add up the items in the second row that correspond to a "1" in the first row.
We get:
2^6+2^4+2^3+2^2+2^1+2^0 = 64+16+8+4+2+1 = 95
Effectively, we add nearly everything in the second row except for the 2^5 term.
Therefore, the number 1011111 base 2 is equivalent to 95 base 10.