O-LevelComputer ScienceData Representation2210/13 · Oct/Nov 2023 · Q213 Marks
Humans use a denary number system and computers use a binary number system.
- (a)Explain what is meant by a binary number system.[2]
- (b)Convert the denary numbers 14, 59 and 234 to binary. 14 59 234 Working space[3]
- (c)Convert the denary numbers 9, 26 and 65 to hexadecimal. 9 26 65 Working space[3]
- (d)Convert the positive denary number 123 to 8-bit binary using two's complement. Show all your working.[2]
- (e)Add the binary values 00110011 and 01111000 using binary addition. Give your answer in binary. Show all your working.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2023). The mark or mark type is shown in brackets.
- [2] (a) Any two from: It has a base of 2, It only uses two values, that are 1 and 0
- [3] (b) (0000)1110, (00)111011, 11101010
- [3] (c) 9, 1A, 41
- [2] (d) One mark for suitable working method e.g. conversion to binary, One mark for correct answer, 01111011
- [3] (e) One mark for each correct nibble (max 2), One mark for correct working e.g. correct carries, 111, 00110011, + 01111000, 1010 1011
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