SECTION 3: Data Representation

Question 1

What number base is binary?

Answer 1

Base 2 (uses only 0 and 1)

Question 2

What number base is decimal?

Answer 2

Base 10 (uses digits 0–9)

Question 3

What number base is hexadecimal?

Answer 3

Base 16 (uses 0–9 and A–F)

Question 4

How do you convert binary to decimal?

Answer 4

Multiply each binary digit by 2ⁿ (starting from the right at n=0) and add the results.

Question 5

How do you convert decimal to binary?

Answer 5

Repeatedly divide by 2 and record the remainders (bottom to top gives binary).

Question 6

How do you convert binary to hexadecimal?

Answer 6

Split binary into 4-bit groups from right, convert each group to hex.

Question 7

How do you convert hexadecimal to binary?

Answer 7

Convert each hex digit into 4-bit binary.

Question 8

How do you convert decimal to hexadecimal?

Answer 8

Convert decimal to binary, then binary to hex (or divide decimal by 16 directly).

Question 9

How do you convert hexadecimal to decimal?

Answer 9

Multiply each hex digit by 16ⁿ (starting from right at n=0) and add the results.

Question 10

What is binary addition?

Answer 10

Adding binary digits using rules: 0+0=0, 0+1=1, 1+1=10 (carry), 1+1+1=11

Question 11

What can binary addition lead to?

Answer 11

Overflow – when result exceeds the storage capacity.

Question 12

What is a binary shift?

Answer 12

Moving binary digits left or right.

Question 13

What does a left binary shift do?

Answer 13

Multiplies the number by 2ⁿ.

Question 14

What does a right binary shift do?

Answer 14

Divides the number by 2ⁿ (loses precision).

Question 15

What is character encoding?

Answer 15

A system that maps characters to binary numbers.

Question 16

What is ASCII?

Answer 16

7-bit character set for English letters, numbers, symbols (128 characters).

Question 17

What is extended ASCII?

Answer 17

8-bit character set (256 characters) including accented letters.

Question 18

What is Unicode?

Answer 18

A universal character set supporting many languages; uses 8–32 bits.

Question 19

Why use Unicode over ASCII?

Answer 19

Supports more symbols and global languages.

Question 20

What is a pixel?

Answer 20

The smallest unit of a digital image.

Question 21

What is resolution?

Answer 21

The number of pixels in an image (width × height).

Question 22

What is colour depth (bit depth)?

Answer 22

The number of bits used to represent the colour of each pixel.

Question 23

What does a higher colour depth allow?

Answer 23

More available colours but a larger file size.

Question 24

What is metadata in an image file?

Answer 24

Extra data such as width, height, colour depth, file type.

Question 25

What is the formula for calculating image file size (in bits)?

Answer 25

Width × Height × Colour depth.

Question 26

How do you convert image file size from bits to bytes/kilobytes?

Answer 26

Divide by 8 for bytes, then divide by 1024 for kilobytes.

Question 27

What is sampling?

Answer 27

Measuring the amplitude of a sound wave at regular intervals.

Question 28

What is the sample rate?

Answer 28

The number of samples taken per second (measured in Hz).

Question 29

What is sample resolution (bit depth)?

Answer 29

The number of bits used to store each sample.

Question 30

What effect does increasing sample rate or resolution have?

Answer 30

Higher quality audio and larger file size.

Question 31

What is the formula for sound file size (in bits)?

Answer 31

Sample rate × Duration × Bit depth × Number of channels.

Question 32

What is data compression?

Answer 32

Reducing the size of a file.

Question 33

Why compress data?

Answer 33

To reduce storage space and speed up transmission.

Question 34

What is lossy compression?

Answer 34

Removes some data permanently to reduce file size.

Question 35

What is lossless compression?

Answer 35

No data is lost; the original file can be fully restored.

Question 36

Give examples of lossy file types.

Answer 36

JPEG, MP3, MP4.

Question 37

Give examples of lossless file types.

Answer 37

PNG, FLAC, ZIP.

Question 38

Advantage of lossy compression?

Answer 38

Smaller file sizes, faster download/upload.

Question 39

Disadvantage of lossy compression?

Answer 39

Reduces quality and cannot restore original.

Question 40

Advantage of lossless compression?

Answer 40

Original quality is preserved.

Question 41

Disadvantage of lossless compression?

Answer 41

File sizes are larger than lossy.

Question 42

What is Huffman coding?

Answer 42

A method of lossless compression that assigns shorter codes to more frequent characters.

Question 43

What is a frequency table in Huffman coding?

Answer 43

A table showing how often each character appears.

Question 44

What is a Huffman tree?

Answer 44

A binary tree built using frequency values, combining least frequent characters first.

Question 45

How do you assign binary codes in a Huffman tree?

Answer 45

Left branch = 0, Right branch = 1; follow from root to leaf.

Question 46

Why is Huffman coding more efficient than ASCII?

Answer 46

It uses fewer bits on average per character.

Question 47

How do you calculate size savings using Huffman vs ASCII?

Answer 47

Compare total bits needed with 8-bit ASCII vs Huffman-assigned codes.

Question 48

What is a bit?

Answer 48

Single binary digit (0 or 1)

Question 49

What is a nibble?

Answer 49

4 bits

Question 50

What is a byte?

Answer 50

8 bit

Question 51

What’s the difference between b and B?

Answer 51

b = bit, B = byte

Question 52

Why use hexadecimal?

Answer 52

Easier to read than binary

Question 53

How many bits does 1 hex digit represent?

Answer 53

4 bits

Question 54

What is RLE?

Answer 54

Stores repeated data as value + count

Question 55

Example of RLE on “AAAABBB”?

Answer 55

4A3B

Question 56

Is RLE lossy or lossless?

Answer 56

Lossless

Question 57

One downside of RLE?

Answer 57

Can increase size if little repetition

Question 58

What is bit rate?

Answer 58

Bits used per second of audio

Question 59

Three uses of hexadecimal:

Answer 59

Colour values in photo editing software/HTML MAC addresses Memory address locations in assembly language