Lesson 4.1.1.6

4.1.1.6 Constants and variables Quiz: AQA Computer Science, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.1.1.6, Constants and variables: 20 multiple choice questions for the AQA Computer Science (7517), Unit 1: Fundamentals of programming, written with Revision Ninja.

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The 20 questions

  1. What is the key difference between a variable and a constant?

    • A variable's value can change while the program runs, but a constant's value cannot
    • A constant is stored in a file on disk, while a variable is never saved to any file
    • A constant's value can change while the program runs, but a variable's value cannot change once set
    • A variable must hold a number, while a constant may hold any type of data such as text

  2. What is the main advantage of using a named constant instead of a literal value?

    • The value can be changed in one place when the rule changes
    • The value no longer needs a data type
    • The program runs faster because the value is cached
    • It allows the value to change while running

  3. Which statement describes a constant?

    • A value that is recalculated on each loop iteration
    • A named value that is fixed once it has been declared
    • A value entered by the user at runtime
    • A memory address stored in a pointer

  4. What does an assignment statement do?

    • Compares two values and returns TRUE or FALSE
    • Stores a value in a variable
    • Calls a subroutine by its name
    • Defines a new data type

  5. Which name follows common convention for a named constant that holds the number of days in a week?

    • daysInWeekCount
    • 7 days in a week
    • DaysInWeekTotalValue
    • DAYS_IN_WEEK

  6. A program reads a constant TAX_RATE and a variable price. Which statement is correct?

    • TAX_RATE can be reassigned, but price cannot
    • Neither can be used in a calculation
    • price can be reassigned, but TAX_RATE cannot
    • Both can be reassigned at any time

  7. What is the purpose of initialising a variable before its first use?

    • So the variable can be shared with an external file without being declared in the code
    • So the variable does not need a data type because its value is known from the start
    • So the variable is automatically converted into a constant for the rest of the program
    • So it starts with a known value rather than an unpredictable one

  8. CONST MAX = 10 is declared, and the code later uses MAX * 2. What is the value?

    • 20
    • 10
    • 5
    • 12

  9. x := 5, then x := x + 3. What is the final value of x?

    • 8
    • 15
    • 3
    • 5

  10. A constant GST_RATE = 0.2 is applied to a price of 50 to find the tax. What is the tax?

    • 15
    • 250
    • 5
    • 10

  11. A program tries to assign a new value to a named constant after it has been declared. What usually happens?

    • The constant is copied to a new memory address and kept
    • The assignment is rejected as an error
    • The constant becomes a variable for the rest of the program
    • The new value silently replaces the constant

  12. To swap the values of variables a and b, which sequence of statements works correctly?

    • a := b; b := a; temp := a
    • temp := a; a := b; b := temp
    • temp := b; a := a; b := temp
    • a := a + b; b := a; temp := b

  13. A variable count is set to 0 and incremented once inside a loop that runs 4 times. What is count at the end?

    • 3
    • 5
    • 0
    • 4

  14. Which identifier is most meaningful for storing the number of students enrolled on a course?

    • numberOfStudents
    • x1, a valid name that says nothing about the value it holds
    • t, a single letter that is often reused for several different values
    • n, a single letter that gives no clue about the value it holds

  15. A program stores the maximum number of players as a named constant, with the value 8. Why is this helpful if the rule might change later?

    • Changing a constant automatically changes all other variables
    • The program will not need to be recompiled
    • The number can be changed by the players during play
    • Only the declaration needs editing rather than every use of the number

  16. A total variable is initialised to 0. Then 5 is added three times and 2 is subtracted once. What is the final total?

    • 3
    • 10
    • 15
    • 13

  17. A constant RATE = 0.05 is applied as compound interest to a balance of 100 for 2 years. What is the balance at the end, to 2 decimal places?

    • 110.00
    • 105.00
    • 110.25
    • 115.50

  18. A program hardcodes the value 25 in six places. The value must change to 30. What is the best approach to avoid six separate edits?

    • Replace the literal with a named constant and change its declaration
    • Store 25 in a Boolean variable instead, so that the value is changed from TRUE to FALSE only
    • Edit each literal separately in every place it appears, checking each one by hand for mistakes
    • Remove all six uses and rely on a default value that the language assigns to every number

  19. A running total is not reset to 0 before a second run of the same calculation. What is the likely effect on the second result?

    • It becomes a constant
    • It is automatically reset by the language
    • It is always zero
    • It includes values left over from the first run

  20. Which is the best justification for declaring a constant PI = 3.14159 rather than using the literal 3.14159 throughout a program?

    • It allows the value to be changed by the user while the program is running, for flexibility
    • It documents the meaning of the value and keeps a single place to change it
    • It makes the program run faster than the literal because the value is cached by the processor
    • It converts the value to an integer automatically, so the decimal places are lost

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