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Signmagnitude repre
sentation
Number
representation in which
the sign represents the
ordering of the number
(negative and positive)
and the value represents
the magnitude
3.2
Representing Numeric Data
57
In general,
n
bits can represent 2
n
things because there are 2
n
combina
tions of 0 and 1 that can be made from
n
bits. Note that every time we
increase the number of available bits by 1, we double the number of things
we 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 because
four bits can represent only 16 things. We would have to use at least five
bits, which would allow us to represent 32 things. Since we only need to
represent 25 things, some of the bit combinations would not have a valid
interpretation.
Keep in mind that even though we may technically need only a certain
minimum number of bits to represent a set of items, we may allocate more
than that for the storage of that data. There is a minimum number of bits
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 Fall '10
 MARIANAKANT

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