OCR
Oxford Cambridge and RSA
GCSE (9-1) Computer Science
Computer Systems
J277/01
Topic: Unit 1.2 Number Conversions
Time allowed: 20 minutes
Centre number
Candidate number
First name
Last name
INSTRUCTIONS
Use black ink.
Answer
all
the questions.
INFORMATION
The total mark for this paper is
16
.
The marks for each question are shown in brackets [ ].
Turn over
1
Convert the following 8-bit binary numbers into Denary.
(a)
0001 0101
[1]
Answer:
(b)
1000 0011
[1]
Answer:
2
Convert the Denary number
170
into an 8-bit Binary number.
Show your working.
[2]
Working:
Answer:
3
Hexadecimal is often used by computer scientists.
(a)
Convert the Binary number
1110 0110
into Hexadecimal.
[1]
Answer:
(b)
Convert the Hexadecimal number
2B
into Binary.
[1]
Answer:
(c)
Explain why computer scientists use Hexadecimal to represent binary numbers.
[2]
Turn over
4
Convert the Hexadecimal number
3E
into Denary.
Show your working.
[2]
Working:
Answer:
5
Convert the Denary number
214
into Hexadecimal.
Show your working.
[2]
Working:
Answer:
6
A student has written the following 4-bit binary number:
1111
.
(a)
State the Denary value of this number.
[1]
(b)
State the Hexadecimal value of this number.
[1]
(c)
Identify the result of adding the binary number
0001
to the student's number (1111).
Give your answer in
4-bit binary
.
[2]
Answer:
END OF QUESTION PAPER