# Subtraction of Unsigned Numbers-2

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Since we are dealing with unsigned numbers, there is really no way to get an unsigned result for the second example. When working with paper and pencil, we recognize that the answer must be changed to a signed negative number. When subtracting with complements, the negative answer is recognized by the absence of the end carry and the complemented result.

Subtraction with complements is done with binary numbers in a similar manner using the same procedure outlined above. Using the two binary numbers X = 1010100 and Y = 1000011, we perform the subtraction X - Y and Y - X using 2's complemenfs:

X= 1010100

2' s complement of Y = +0111101

Sum = 10010001

Discard end carry 27 = - 10000000

Answer: X - Y = 0010001

y = 1000011

2's complement of X = +0101 100

Sum = 1101111

There is no end carry

Answer is negative 0010001 = 2's complement of 1101111

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