IGCSE 0478/2210
Computer science
Unit 1 – Data Representation
Revision questions and answers
(Questions from different IGCSE books)
K. Chitra
Computer Science Teacher
https://www.youtube.com/@codewithchittu1095
www.linkedin.com/in/codewithchittu
1|Page
,1. State what is meant by analogue data?
Data that is recorded in a form that is similar to its original structure.
2. State what is meant by digital data?
Digital data is information stored on a computer system as a series of 0's and 1's in a binary
language
3. Describe the difference between denary number system and binary number system.
– Denary number system is used by humans, deals with 10 numbers (0 to 9)
– It is referred as Base 10
– Binary number system is used by computers, deals with only 2 numbers(
0 and 1) It is referred as Base 2
4. What is the largest denary number that can be created with a 4 bit binary number ?
1111 ------- 15
5. Convert the denary number 6 to a 4-bit binary number
0110
6. Convert the denary number 9 to a 4-bit binary number
1001
7. What is the largest denary number that can be created with a 8 bit binary number ?
11111111 = 128
8. Convert the binary number 100111010001 to hexadecimal number?
9D1
9. What happens in a logical binary shift?
There are two logical shifts. Left shift and Right shift.
Left Shift : a binary shift moves all the digits in the binary number along to the left and fills
the gaps after the shift with 0. Actually, it is multiplying by 2.
– to multiply by two, all digits shift one place to the left
– to multiply by four, all digits shift two places to the left
– to multiply by eight, all digits shift three places to the left
Right Shift: To divide a number, a binary shift moves all the digits in the binary number
along to the right and fills the gaps after the shift with 0:
– to divide by two, all digits shift one place to the right
– to divide by four, all digits shift two places to the right
– to divide by eight, all digits shift three places to the right
– and so on
10. How many times would you need to divide the answer in bytes by 1024 to find
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, answer in Gibibytes?
I need to divide 3 times the answer in bytes to get answer in Gibibytes.
11. How many pixels would there be in an image that has a resolution of 1000 X 1500?
1500000 pixels
12. The software developer is using 16-colour bitmap images. How many bits would
be used to encode data for one pixel of his image? [1 mark]
4 bits
13. What is the minimum colour depth of a bitmapped graphic that has 64 colours?
The answer is 6 bits.
Working out: Each colour is assigned a unique binary code.
– With 6 bits, 26 = 64. Thus, 64 different colours can be represented.
14. What is meant by image resolution?
Image resolution is the number of pixels in an image contains per inch.
15. What is the file size of a bitmapped graphic that is 6 × 4 pixels and has a colour
depth of 2 bits?
48 bits
Working out: Calculate total bits: 6 × 4 × 2 = 48 bits
16. What is the file size of a bitmapped graphic that is 800 × 800 pixels and has a
colour depth of 4 bits?
Give your answer in kB. Assume that 1kB = 1000
bytes. Write down your workings before you reveal
the answer.
320kB
Working out:
– Calculate total bits: 800 × 800 × 4 = 2,560,000 bits
– Convert bits to bytes: 2,560, = 320,000 bytes
– Convert bytes to kilobytes: 320, = 320kB
17. What is meta data?
The actual file size of a bitmapped graphic is always greater than the result of its
simple file size calculation. This is because, in addition to the pixel data, the file must store
additional information so that the image can be reproduced accurately. This additional data
is called metadata, which means data about data.
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Computer science
Unit 1 – Data Representation
Revision questions and answers
(Questions from different IGCSE books)
K. Chitra
Computer Science Teacher
https://www.youtube.com/@codewithchittu1095
www.linkedin.com/in/codewithchittu
1|Page
,1. State what is meant by analogue data?
Data that is recorded in a form that is similar to its original structure.
2. State what is meant by digital data?
Digital data is information stored on a computer system as a series of 0's and 1's in a binary
language
3. Describe the difference between denary number system and binary number system.
– Denary number system is used by humans, deals with 10 numbers (0 to 9)
– It is referred as Base 10
– Binary number system is used by computers, deals with only 2 numbers(
0 and 1) It is referred as Base 2
4. What is the largest denary number that can be created with a 4 bit binary number ?
1111 ------- 15
5. Convert the denary number 6 to a 4-bit binary number
0110
6. Convert the denary number 9 to a 4-bit binary number
1001
7. What is the largest denary number that can be created with a 8 bit binary number ?
11111111 = 128
8. Convert the binary number 100111010001 to hexadecimal number?
9D1
9. What happens in a logical binary shift?
There are two logical shifts. Left shift and Right shift.
Left Shift : a binary shift moves all the digits in the binary number along to the left and fills
the gaps after the shift with 0. Actually, it is multiplying by 2.
– to multiply by two, all digits shift one place to the left
– to multiply by four, all digits shift two places to the left
– to multiply by eight, all digits shift three places to the left
Right Shift: To divide a number, a binary shift moves all the digits in the binary number
along to the right and fills the gaps after the shift with 0:
– to divide by two, all digits shift one place to the right
– to divide by four, all digits shift two places to the right
– to divide by eight, all digits shift three places to the right
– and so on
10. How many times would you need to divide the answer in bytes by 1024 to find
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, answer in Gibibytes?
I need to divide 3 times the answer in bytes to get answer in Gibibytes.
11. How many pixels would there be in an image that has a resolution of 1000 X 1500?
1500000 pixels
12. The software developer is using 16-colour bitmap images. How many bits would
be used to encode data for one pixel of his image? [1 mark]
4 bits
13. What is the minimum colour depth of a bitmapped graphic that has 64 colours?
The answer is 6 bits.
Working out: Each colour is assigned a unique binary code.
– With 6 bits, 26 = 64. Thus, 64 different colours can be represented.
14. What is meant by image resolution?
Image resolution is the number of pixels in an image contains per inch.
15. What is the file size of a bitmapped graphic that is 6 × 4 pixels and has a colour
depth of 2 bits?
48 bits
Working out: Calculate total bits: 6 × 4 × 2 = 48 bits
16. What is the file size of a bitmapped graphic that is 800 × 800 pixels and has a
colour depth of 4 bits?
Give your answer in kB. Assume that 1kB = 1000
bytes. Write down your workings before you reveal
the answer.
320kB
Working out:
– Calculate total bits: 800 × 800 × 4 = 2,560,000 bits
– Convert bits to bytes: 2,560, = 320,000 bytes
– Convert bytes to kilobytes: 320, = 320kB
17. What is meta data?
The actual file size of a bitmapped graphic is always greater than the result of its
simple file size calculation. This is because, in addition to the pixel data, the file must store
additional information so that the image can be reproduced accurately. This additional data
is called metadata, which means data about data.
3|Page
