3.- Two's Complement. Signed numbers.
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We have the number 177, we convert it to binary and we obtain:
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If we convert that number to signed binary, it turns out that the left bit becomes a sign and the numerical value corresponds to the two's complement of the other 7 bits.
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Two's complement, it results from inverting the bits and adding a 1 to the number obtained:
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We make this change when the number we want to convert is greater than 127.
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One way to obtain the decimal number is to subtract it from 256, that is
256 - 177 = 79