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Year 8 Computing — Adding binary numbers

Add two binary numbers place by place, carrying into the next place whenever a column comes to more than one.

Name: ________________________

  1. 1.Which of these additions gives an answer with more places than both of the numbers being added?

    • a) "11" and "1"
    • b) "101" and "10"
    • c) "100" and "11"
    • d) "10" and "1"

  2. 2.Put these binary additions in order of their answers, smallest first.

    • 110 + 100
    • 10 + 1
    • 11 + 10
    • 1000 + 101
    • 100 + 11

  3. 3.Add the binary numbers "110" and "11". Write the answer in binary.

  4. 4.Adding "111" and "1" gives an answer with how many binary places?

    • a) 4
    • b) 5
    • c) 3
    • d) 2

  5. 5.Add the binary numbers "1010" and "1010". Write the answer in binary.

  6. 6.Match each binary addition to its answer.

    • 1 + 10
    • 11 + 11
    • 100 + 100
    • 101 + 10
    • 1001 + 11
    • 1100
    • 11
    • 1000
    • 111
    • 110

  7. 7.Sort each addition by whether its right-hand column produces a carry.

    Groups: Produces a carry · No carry

    • 11 + 1
    • 100 + 10
    • 101 + 11
    • 10 + 1
    • 1000 + 111
    • 1001 + 1001

  8. 8.Add the binary numbers "110" and "10". Write the answer in binary.

Answer key — Year 8 Computing — Adding binary numbers

  1. 1. a) "11" and "1"
  2. 2. 1. 10 + 1 2. 11 + 10 3. 100 + 11 4. 110 + 100 5. 1000 + 101
  3. 3. 1001
  4. 4. a) 4
  5. 5. 10100
  6. 6. 1 + 10 → 11; 11 + 11 → 110; 100 + 100 → 1000; 101 + 10 → 111; 1001 + 11 → 1100
  7. 7. 1001 + 1001 → Produces a carry; 10 + 1 → No carry; 11 + 1 → Produces a carry; 100 + 10 → No carry; 101 + 11 → Produces a carry; 1000 + 111 → No carry
  8. 8. 1000