O-LevelComputer ScienceData Representation2210/12 · Oct/Nov 2025 · Q27 Marks
Two binary numbers are stored in a computer.
- (a)Add the two binary numbers using binary addition. Give your answer in binary. Show all of your working. 11110101 + 00111001[4]
- (b)A logic right shift of three places is performed on the binary number 11110101. Give the denary number for the binary number that would be stored after the logical shift of three places has occurred. Show all of your working.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2025). The mark or mark type is shown in brackets.
- [4] One mark for each correct nibble (2) // One mark for a correct method of working for example 4 or 5 correct carries // One mark for showing an overflow error (1) 111 1 // 11110101 // + 00111001 // 1 0010 1110
- [3] One mark for showing the binary number after the shift // One mark for valid method of working to convert to denary // One mark for correct denary number • 00011110 • 16+8+4+2 • 30
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