2026 AQA A LEVEL COMPUTER SCIENCE
UPDATED ACTUAL EXAM QUESTIONS AND
CORRECT ANSWERS FULL SOLUTION
GRADED A+
◉ Natural Numbers (N). Answer: Positive Integers; N = {0, 1, 2, 3,
...}
◉ Integer Numbers (Z). Answer: Whole numbers; Z = {..., -1, 0, 1,
...}
◉ Rational Numbers (Q). Answer: Numbers that can be represented
as a fraction (all integers are rational)
◉ Irrational Numbers. Answer: Numbers that cannot be represented
as a fraction
◉ Real Numbers (R). Answer: A number that exists (so not a
conceptual number like Pi)
◉ Ordinal Numbers. Answer: The positions used in lists (1, 2, 3, ...)
,◉ Base. Answer: The number of symbols used to construct values
(also referred to as a subscript)
◉ Base 2 (Binary). Answer: A number system that uses 2 symbols, 0
& 1. Numbers in base 2 are written as X(v2) such as 11(v2)
representing 3.
◉ Binary Representation of Numbers. Answer: The Binary system
uses 2x to represent numbers, with x increasing by one every place,
starting from the rightmost place. (So 1, 2, 4, 8, 16, 32, 64, 128)
◉ Base 10 (Decimal). Answer: A number system that uses 10
symbols, 0-9. Numbers in base 10 are written as X(v10) such as
11(v10) representing 11.
◉ Decimal Representation of Numbers. Answer: The Decimal system
uses 10x to represent numbers, with x increasing by one every place,
starting from the rightmost place. (So 1, 10, 100)
◉ Base 16 (Hexadecimal). Answer: A number system that uses 16
symbols, 0-9 & A-F. Numbers in base 16 are written as X(v16) such
as 11(v16) representing 17.
◉ Hexadecimal Representation of Numbers. Answer: The
Hexadecimal system uses 16x to represent numbers, with x increasing
by one every place, starting from the rightmost place. (So 1, 16, 256)
,◉ Why use Hex?. Answer: A hex number is easier to read and
remember than binary, and so is quicker to accurately write or type. It
has easy conversion. It is used to define colours, in MAC addresses
and, machine code.
◉ Decimal to Binary Conversion. Answer: From left to right in the
place value table, subtract the place value from the decimal number
where possible.
◉ Decimal to Hex Conversion. Answer: Divide the decimal number
by 16, and add the remainder.
◉ Significance of 16. Answer: 16 is 24, meaning that base 16
numbers can be translated from 4 consecutive bits of a binary value.
This makes it simple to translate binary numbers into hexadecimal
values and back again.
◉ Bits. Answer: Each individual digit in a binary digit is referred to
as a bit, from the term binary digit
◉ Bytes. Answer: A collection of 8 bits
◉ Kilobyte. Answer: KB, 10^3 bytes
◉ Megabyte. Answer: MB, 10^6 bytes
, ◉ Gigabyte. Answer: GB, 10^9 bytes
◉ Terabyte. Answer: TB, 10^12 bytes
◉ Kibibyte. Answer: KiB, 2^10 bytes
◉ Mebibyte. Answer: MiB, 2^20 bytes
◉ Gibibyte. Answer: GiB, 2^30 bytes
◉ Tebibytes. Answer: Tib, 2^40 bytes
◉ ASCII Code. Answer: In 1963, the American Standard Code for
Information Interchange, was established to encode symbols found in
the English alphabet. Important ASCII values: A = 65, a = 97
◉ Unicode. Answer: The Unicode system was introduced to
standardise the encoding of characters from all languages
◉ Transmission errors. Answer: When data is transmitted, it doesn't
always arrive in the same format that it was sent. These errors cause
bits to flip from 1s to 0s and vice versa.
◉ What causes Transmission errors?. Answer: Electrical interference,
power surges, synchronisation issues, broken cables and connectors
UPDATED ACTUAL EXAM QUESTIONS AND
CORRECT ANSWERS FULL SOLUTION
GRADED A+
◉ Natural Numbers (N). Answer: Positive Integers; N = {0, 1, 2, 3,
...}
◉ Integer Numbers (Z). Answer: Whole numbers; Z = {..., -1, 0, 1,
...}
◉ Rational Numbers (Q). Answer: Numbers that can be represented
as a fraction (all integers are rational)
◉ Irrational Numbers. Answer: Numbers that cannot be represented
as a fraction
◉ Real Numbers (R). Answer: A number that exists (so not a
conceptual number like Pi)
◉ Ordinal Numbers. Answer: The positions used in lists (1, 2, 3, ...)
,◉ Base. Answer: The number of symbols used to construct values
(also referred to as a subscript)
◉ Base 2 (Binary). Answer: A number system that uses 2 symbols, 0
& 1. Numbers in base 2 are written as X(v2) such as 11(v2)
representing 3.
◉ Binary Representation of Numbers. Answer: The Binary system
uses 2x to represent numbers, with x increasing by one every place,
starting from the rightmost place. (So 1, 2, 4, 8, 16, 32, 64, 128)
◉ Base 10 (Decimal). Answer: A number system that uses 10
symbols, 0-9. Numbers in base 10 are written as X(v10) such as
11(v10) representing 11.
◉ Decimal Representation of Numbers. Answer: The Decimal system
uses 10x to represent numbers, with x increasing by one every place,
starting from the rightmost place. (So 1, 10, 100)
◉ Base 16 (Hexadecimal). Answer: A number system that uses 16
symbols, 0-9 & A-F. Numbers in base 16 are written as X(v16) such
as 11(v16) representing 17.
◉ Hexadecimal Representation of Numbers. Answer: The
Hexadecimal system uses 16x to represent numbers, with x increasing
by one every place, starting from the rightmost place. (So 1, 16, 256)
,◉ Why use Hex?. Answer: A hex number is easier to read and
remember than binary, and so is quicker to accurately write or type. It
has easy conversion. It is used to define colours, in MAC addresses
and, machine code.
◉ Decimal to Binary Conversion. Answer: From left to right in the
place value table, subtract the place value from the decimal number
where possible.
◉ Decimal to Hex Conversion. Answer: Divide the decimal number
by 16, and add the remainder.
◉ Significance of 16. Answer: 16 is 24, meaning that base 16
numbers can be translated from 4 consecutive bits of a binary value.
This makes it simple to translate binary numbers into hexadecimal
values and back again.
◉ Bits. Answer: Each individual digit in a binary digit is referred to
as a bit, from the term binary digit
◉ Bytes. Answer: A collection of 8 bits
◉ Kilobyte. Answer: KB, 10^3 bytes
◉ Megabyte. Answer: MB, 10^6 bytes
, ◉ Gigabyte. Answer: GB, 10^9 bytes
◉ Terabyte. Answer: TB, 10^12 bytes
◉ Kibibyte. Answer: KiB, 2^10 bytes
◉ Mebibyte. Answer: MiB, 2^20 bytes
◉ Gibibyte. Answer: GiB, 2^30 bytes
◉ Tebibytes. Answer: Tib, 2^40 bytes
◉ ASCII Code. Answer: In 1963, the American Standard Code for
Information Interchange, was established to encode symbols found in
the English alphabet. Important ASCII values: A = 65, a = 97
◉ Unicode. Answer: The Unicode system was introduced to
standardise the encoding of characters from all languages
◉ Transmission errors. Answer: When data is transmitted, it doesn't
always arrive in the same format that it was sent. These errors cause
bits to flip from 1s to 0s and vice versa.
◉ What causes Transmission errors?. Answer: Electrical interference,
power surges, synchronisation issues, broken cables and connectors
