Sign-magnitude repre-sentationNumberrepresentation in whichthe sign represents theordering of the number(negative and positive)and the value representsthe magnitude3.2Representing Numeric Data57In general, nbits can represent 2nthings because there are 2ncombina-tions of 0 and 1 that can be made from nbits. Note that every time weincrease the number of available bits by 1, we double the number of thingswe can represent.Let’s turn the question around. How many bits do you need to repre-sent, say, 25 unique things? Well, four bits wouldn’t be enough becausefour bits can represent only 16 things. We would have to use at least fivebits, which would allow us to represent 32 things. Since we only need torepresent 25 things, some of the bit combinations would not have a validinterpretation.Keep in mind that even though we may technically need only a certainminimum number of bits to represent a set of items, we may allocate morethan that for the storage of that data. There is a minimum number of bits
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