5 (a) Convert the hexadecimal number A3 to denary - OCR - GCSE Computer Science - Question 5 - 2019 - Paper 1

To convert the binary number 1011011 to denary, we identify the positional values:

• The binary number is written as:

$1 \times 2^6 + 0 \times 2^5 + 1 \times 2^4 + 1 \times 2^3 + 0 \times 2^2 + 1 \times 2^1 + 1 \times 2^0$

Calculating each term results in:

$64 + 0 + 16 + 8 + 0 + 2 + 1 = 91$

Therefore, the denary representation of binary 1011011 is 91.

To add the binary numbers 1010110 and 1000111:

    1010110
  + 1000111
  ----------
   10011001

To carry out the addition from right to left:

• 0 + 1 = 1
• 1 + 1 = 0 (carry over 1)
• 1 + 1 + 1 = 1 (carry 1)
• 0 + 0 + 1 = 1
• 1 + 0 = 1
• 0 + 1 = 1
• 1 + 1 = 0 (carry over 1)
• Finally, write down the carry 1 to the leftmost side.

Thus, the result of adding 1010110 and 1000111 is 10011001.