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Homework Help: Subtraction using 8-bit binary 1's complement

  1. Apr 12, 2015 #1
    1. The problem statement, all variables and given/known data
    Perform the indicated subtraction using 8-bit binary in 1's complement:



    2. Relevant equations
    i. Convert the numbers from decimal to binary
    ii. Take the ones complement of binary representation of any negative numbers
    iii. Add the two numbers together add 1 if there is a carryout. Leave as is if no carry out.
    3. The attempt at a solution
    (+22)10 →→ (0001 0110)2 →→ (0001 0110)2
    +(-59)10 → +1'sC(0011 1011)2 → +(1100 0100)2
    Answer: (1101 1010)2

    (-11) →→1'sC(0000 1011)→1111 0100
    +(-64) →+1'sC(0100 0000) →+1011 1111
    Answer: 1011 0100

    Is this correct? Thanks. I just get the positive value by taking the 1's Comp of my answer right? I kind of figured it out as I wrote this. But if someone can confirm that would be nice thanks.
    Last edited: Apr 12, 2015
  2. jcsd
  3. Apr 12, 2015 #2


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    Gold Member

    I only checked the first one and it looks fine.
  4. Apr 12, 2015 #3
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