Playing as a guest? to earn XP and track your progress.
Data Representation Quiz
Data Representation
Why do computers use the binary number system internally?
Because humans find binary easy to read
Because binary can store more data than decimal
Because their electronic switches have only two states, ON and OFF
Because binary numbers are shorter than decimal numbers
Computers are built from millions of switches (transistors) that can only be ON (1) or OFF (0), so all data is represented as 0s and 1s.
The base (radix) of a number system is:
The number of bits in a byte
The total count of unique digits it uses
The value of its leftmost digit
The largest number it can represent
A number system's base, or radix, is the total count of unique digits used — for example 10 in decimal and 2 in binary.
What are the bases of the binary, octal and hexadecimal number systems?
2, 8, 16
2, 8, 10
2, 10, 16
1, 8, 16
Binary is base 2, octal is base 8, hexadecimal is base 16 (and decimal is base 10).
Which number system uses only the digits 0 to 7?
Binary
Decimal
Hexadecimal
Octal
Octal (base 8) uses the eight digits 0, 1, 2, 3, 4, 5, 6 and 7.
Which symbols does the hexadecimal system use?
A-P
0-9 only
0-9 and A-F
0-7 and A-H
Hexadecimal uses 16 digits: 0-9 followed by A, B, C, D, E, F (A=10 ... F=15).
What is the decimal value of the hexadecimal digit D?
12
13
11
14
In hexadecimal A=10, B=11, C=12, D=13, E=14 and F=15.
In the decimal number 253, what is the positional value of the digit 5?
50
5
5 × 10²
500
253 = 2×10² + 5×10¹ + 3×10⁰, so the 5 is in the tens place and is worth 50.
What is a single binary digit called?
Nibble
Byte
Word
Bit
Each binary digit is called a BIT (Binary Digit).
How many bits make up one byte?
2
16
8
4
8 bits together make 1 byte.
What is the decimal value of (1011)₂?
9
11
1011
13
(1×8) + (0×4) + (1×2) + (1×1) = 11.
What is the decimal value of (10110)₂?
22
11
26
20
(1×16)+(0×8)+(1×4)+(1×2)+(0×1) = 16+4+2 = 22.
What is the decimal value of (11010)₂?
13
28
24
26
(1×16)+(1×8)+(0×4)+(1×2)+(0×1) = 16+8+2 = 26.
What is the decimal value of (101010)₂?
40
21
42
84
32 + 8 + 2 = 42 (the 1s are in the 2⁵, 2³ and 2¹ positions).
Which method converts a decimal number to binary?
Repeated division by 2, reading the remainders top to bottom
Repeated division by 2, reading the remainders bottom to top
Group the digits in threes
Multiply by 2 and add the digits
Divide repeatedly by 2, note each remainder, then read the remainders from bottom to top.
What is (25)₁₀ in binary?
11001
10101
11010
10011
25→12 r1, 12→6 r0, 6→3 r0, 3→1 r1, 1→0 r1. Reading bottom to top gives 11001.
A student converts (25)₁₀ to binary and gets (10011)₂. What mistake did they make?
They added instead of multiplying
They forgot to pad with zeros
They divided by 8 instead of 2
They read the remainders from top to bottom instead of bottom to top
The correct answer is 11001. 10011 is its reverse, the classic result of reading remainders top to bottom.
What is (45)₁₀ in binary?
101011
110101
101101
100101
45→22 r1, 22→11 r0, 11→5 r1, 5→2 r1, 2→1 r0, 1→0 r1. Bottom to top: 101101.
What is (37)₁₀ in binary?
100011
100101
110001
101001
37 = 32 + 4 + 1, so the bits for 2⁵, 2² and 2⁰ are 1: 100101.
When converting decimal to binary, the FIRST remainder you calculate becomes:
The last (rightmost) digit of the answer
The first (leftmost) digit of the answer
The middle digit
It is discarded
Remainders are read bottom to top, so the first remainder calculated is the last (rightmost) digit.
What is (100)₁₀ in octal?
124
441
64
144
100÷8 = 12 r4, 12÷8 = 1 r4, 1÷8 = 0 r1. Bottom to top: 144.
What is the decimal value of (144)₈?
144
96
100
112
(1×64) + (4×8) + (4×1) = 64 + 32 + 4 = 100.
What is the decimal value of (372)₈?
258
250
242
372
(3×64) + (7×8) + (2×1) = 192 + 56 + 2 = 250.
What is the decimal value of (57)₈?
47
40
45
57
(5×8) + (7×1) = 40 + 7 = 47.
What is (64)₁₀ in octal?
10
64
80
100
64÷8 = 8 r0, 8÷8 = 1 r0, 1÷8 = 0 r1. Bottom to top: 100 (since 64 = 8²).
Why does exactly one octal digit correspond to 3 binary digits?
Because 3 × 8 = 24
Because octal has 3 symbols
Because 8 = 2³
Because binary uses 3 digits
Since 8 = 2³, each octal digit maps to exactly 3 bits.
What is (372)₈ in binary?
011 101 010
011 111 010
010 111 011
111 011 010
Expand each octal digit to 3 bits: 3→011, 7→111, 2→010, giving 011111010.
What is the 3-bit binary equivalent of the octal digit 6?
110
011
111
101
6 = 4 + 2, so its 3-bit form is 110.
What is (746)₈ in binary?
111 010 110
111 100 101
110 100 111
111 100 110
7→111, 4→100, 6→110, giving 111100110.
To convert binary to octal, you should:
Divide by 8 repeatedly
Group the bits in 4s from the left
Group the bits in 3s from the right
Group the bits in 3s from the left
Group binary digits in sets of 3 starting from the RIGHT, padding with zeros on the left if needed.
What is (11111010)₂ in octal?
762
372
FA
352
Group in 3s from the right: 011 111 010 → 3, 7, 2 = 372.
What is (110101)₂ in octal?
65
53
35
56
Group in 3s from the right: 110 101 → 6, 5 = 65.
When grouping (11111010)₂ into 3s, the leftmost group '11' is written as:
110
111
It is dropped
011
Pad with zeros on the LEFT to complete the group — 11 becomes 011, which does not change the value.
What is (250)₁₀ in hexadecimal?
E10
F10
FA
AF
250÷16 = 15 r10 (A), 15÷16 = 0 r15 (F). Bottom to top: FA.
What is the decimal value of (2A)₁₆?
32
42
26
210
(2×16) + (10×1) = 32 + 10 = 42.
What is the decimal value of (FA)₁₆?
250
240
225
255
(15×16) + (10×1) = 240 + 10 = 250.
What is the decimal value of (BC)₁₆?
192
176
187
188
(B×16) + C = (11×16) + 12 = 176 + 12 = 188.
What is (100)₁₀ in hexadecimal?
A0
144
64
46
100÷16 = 6 r4, 6÷16 = 0 r6. Bottom to top: 64.
Why does exactly one hexadecimal digit correspond to 4 binary digits?
Because 4 × 4 = 16 bits
Because 16 = 2⁴
Because a byte has 4 bits
Because hex uses 4 letters
Since 16 = 2⁴, each hex digit maps to exactly 4 bits, which makes hex a compact way to write binary.
What is (11111010)₂ in hexadecimal?
FA
372
F5
AF
Group in 4s from the right: 1111 1010 → F, A = FA.
What is (11011010)₂ in hexadecimal?
332
AD
CA
DA
Group in 4s: 1101 1010 → D, A = DA.
What is (11011010)₂ in octal?
DA
632
332
323
Group in 3s from the right: 011 011 010 → 3, 3, 2 = 332.
What is (10110110)₂ in hexadecimal?
6B
B6
266
A6
Group in 4s: 1011 0110 → B, 6 = B6.
What is (3C)₁₆ in binary?
0011 1100
0111 1100
0011 1010
1100 0011
Expand each hex digit to 4 bits: 3→0011, C→1100.
What is the 4-bit binary form of the hex digit 9?
0110
1010
1100
1001
9 = 8 + 1, so its 4-bit form is 1001.
How should an octal number be converted to hexadecimal?
It cannot be converted
By multiplying each digit by 2
Always through binary as the middle step
Directly, digit by digit
There is no direct shortcut: convert octal to binary (3 bits per digit), then group the bits in 4s to get hex.
What is (17)₈ in hexadecimal?
11
F
17
E
Octal 17 → binary 001 111 → regroup in 4s as 1111 → F (decimal 15).
What are the binary, octal and hexadecimal forms of (156)₁₀?
10011100, 234, 9C
10011100, 243, C9
10011010, 234, 9A
11001100, 324, CC
Repeated division gives binary 10011100, octal 234 and hexadecimal 9C.
What is (78)₁₀ in hexadecimal?
4D
E4
116
4E
78÷16 = 4 r14 (E), 4÷16 = 0 r4. Bottom to top: 4E.
What does ASCII stand for?
Automatic Standard Code for Information Input
Advanced System Code for Internal Instructions
American Standard Code for Information Interchange
American Script Character for International Interchange
ASCII is the American Standard Code for Information Interchange.
Standard 7-bit ASCII can represent values in which range?
1 to 128
0 to 127
0 to 65535
0 to 255
Standard ASCII uses 7 bits, giving values 0-127; extended 8-bit ASCII gives 0-255.
What is the ASCII value of 'A'?
65
97
64
48
'A' has ASCII value 65 (binary 01000001).
If 'Z' has ASCII value 90, what is the ASCII value of 'z'?
58
96
120
122
Lowercase value = uppercase value + 32, so 90 + 32 = 122.
What is the ASCII value of the character '0' (digit zero)?
30
0
48
65
The digits '0' to '9' have ASCII values 48 to 57.
What is ISCII designed for?
Representing only numbers
Representing Indian language scripts such as Devanagari and Tamil
Compressing English text
Representing every world language and emojis
ISCII (Indian Script Code for Information Interchange) is an 8-bit code created to represent Indian language characters that ASCII cannot handle.
Which character encoding can represent characters from every world language, including emojis?
Unicode
ASCII
Octal
ISCII
Unicode is a universal standard covering every major world language, symbols and emojis.
Which statement about Unicode and ASCII is correct?
They are exactly the same standard
Unicode is smaller than ASCII
ASCII covers Hindi and Chinese
Unicode's first 128 values are identical to ASCII
Unicode is backward compatible: its first 128 values match ASCII.
Which encoding lets one document mix English, Hindi, Chinese and emojis?
Binary
ASCII
Unicode
ISCII
Only Unicode, a single universal standard, lets multiple languages and emojis appear together.
Strings in Python 3 are stored using which encoding by default?
Octal
Unicode
ISCII
ASCII
Python 3 strings are Unicode by default.
Which colour code format used in CSS/web design is written in hexadecimal?
FF5733
0o17
rgb%
0b1010
Web colour codes such as #FF5733 are written in hexadecimal.