WAEC Computer Studies 2021 past questions

Checked by the Skolra question team · Last updated 23 October 2026

Ten questions from the 2021 WAEC Computer Studies paper, with answers and explanations. We hold 36 questions from this paper, and the Skolra app has all of them.

WAEC Computer Studies 2021 questions and answers

1. 1.A collection of wires through which data are transmitted from one part of the computer to another is known as
   1. A
      Circuit
   2. B
      Bus
      Correct
   3. C
      Cable
   4. D
      Port
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   Answer: B

   In computer architecture, the bus is the collection of wires (lines) that carries data, addresses and control signals from one part of the computer to another, for example between the CPU, memory and input/output devices. Computer systems typically have a data bus, an address bus and a control bus working together.

2. 2.In MS Excel, the cell that contains the pointer or cursor is called
   1. A
      Active cell
      Correct
   2. B
      Name box
   3. C
      Cell reference
   4. D
      Formula bar
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   Answer: A

   In MS Excel, the cell that currently holds the pointer or cursor, and into which anything typed will be entered, is called the active cell. It is usually shown with a bold border around it, and its address appears in the Name Box.

3. 3.Evaluate 10011$_2$ - 1111$_2$
   1. A
      110₂
   2. B
      1100₂
   3. C
      101₂
   4. D
      100₂
      Correct
   Show answerHide answer

   Answer: D

   Convert both numbers to base 10 first. 10011₂ = (1×16) + (0×8) + (0×4) + (1×2) + (1×1) = 19. 1111₂ = (1×8) + (1×4) + (1×2) + (1×1) = 15.

   19 − 15 = 4, and 4 in binary is written as 100₂. That is the correct result.

   Working it directly in binary with borrowing confirms this:

     10011
    − 01111
     ______
     00100

4. 4.Write a QBASIC program to grade any score entered from the keyboard as either "Poor" for a score that is below 50% or "Satisfactory" for a score that is equal to or above 50%. The program execution should stop as soon as a score that is less than zero is entered.
   1. A
      DO INPUT "Enter score"; S IF S < 0 THEN END IF S < 50 THEN PRINT "Poor" ELSE PRINT "Satisfactory" END IF LOOP
      Correct
   2. B
      DO INPUT "Enter score"; S IF S < 0 THEN END IF S < 50 THEN PRINT "Satisfactory" ELSE PRINT "Poor" END IF LOOP
   3. C
      DO INPUT "Enter score"; S IF S < 0 THEN END IF S <= 50 THEN PRINT "Poor" ELSE PRINT "Satisfactory" END IF LOOP
   4. D
      DO INPUT "Enter score"; S IF S <= 0 THEN END IF S < 50 THEN PRINT "Poor" ELSE PRINT "Satisfactory" END IF LOOP
   Show answerHide answer

   Answer: A

   The task has three parts that the program must get right: (1) keep asking for a score repeatedly, (2) stop as soon as a score less than zero is entered, and (3) grade every other score as "Poor" when it is below 50, or "Satisfactory" when it is 50 or above.

5. 5.A computer program that gathers information about a person or organization without their knowledge or consent is known known as
   1. A
      Adware
   2. B
      Computer worm
   3. C
      Trojan horse
   4. D
      Spyware
      Correct
   Show answerHide answer

   Answer: D

   Spyware is correct. It is a program that installs itself on a computer and secretly gathers information about a person or organisation—such as browsing habits, passwords or files—and sends it to another party without the owner's knowledge or consent.

6. 6.What factors will motivate a field engineer into choosing anotebook computer over adesktop computer?
   1. A
      Larger storage capacity, bigger screen size and faster processing speed
   2. B
      Lower purchase cost, easier hardware upgrade and a full-size keyboard
   3. C
      Portability, light weight and the ability to run on battery power away from mains electricity
      Correct
   4. D
      Better cooling system, more expansion slots and a more stable network connection
   Show answerHide answer

   Answer: C

   A field engineer works away from the office, often moving between sites where there may be no fixed power supply or desk space. Portability, light weight and the ability to run on battery power away from mains electricity are what make a notebook computer suitable for that kind of work: it can be carried in a bag, used on site, and powered from its own battery until electricity or a generator is available.

7. 7.Which of the following statements is true about super computers? They
   1. A
      have less processing power and memory capacity than mainframe computers
   2. B
      are the fastest and most powerful type of computer, used mainly for complex scientific computations
      Correct
   3. C
      are designed mainly for simple tasks such as word processing and data entry
   4. D
      are smaller and cheaper than personal computers, making them common in homes
   Show answerHide answer

   Answer: B

   Supercomputers are the fastest, most powerful and most expensive class of computers in existence. They are built with thousands of processors working in parallel, giving them extremely high processing speed, which is why they are used for complex scientific and engineering computations such as weather forecasting, climate research, nuclear simulations, and cryptography.

8. 8.The operation of a computer and peripherals attached to it is controlled by
   1. A
      Memory unit
   2. B
      Arithmetic and Logic Unit (ALU)
   3. C
      Operating system
   4. D
      Control unit
      Correct
   Show answerHide answer

   Answer: D

   Control unit is correct.

   The Control Unit (CU) is the part of the Central Processing Unit (CPU) that directs and coordinates the operations of the whole computer system. It fetches instructions from memory, decodes them, and then sends out control signals along the control bus telling the other parts of the system — including the Arithmetic and Logic Unit, the memory, and every peripheral device attached (keyboard, monitor, printer, disk drives, etc.) — what to do and exactly when to do it. This is why it is described as controlling "the operation of a computer and the peripherals attached to it".

9. 9.The IF... THEN statement in BASIC is called
   1. A
      a looping statement
   2. B
      a conditional statement
      Correct
   3. C
      an unconditional statement
   4. D
      an assignment statement
   Show answerHide answer

   Answer: B

   In BASIC programming, statements are grouped by the control structure they belong to: sequence, selection and repetition.

10. 10.Perform the following conversions in the stated number bases; (a) AB1$_{16}$ to Octal system (b) 1110111.101$_2$ to Denary system (c) 507$_8$ to Binary system.
    1. A
       (a) 5261₈ (b) 119.625₁₀ (c) 1010111₂
    2. B
       (a) 5261₈ (b) 119.101₁₀ (c) 101000111₂
    3. C
       (a) 5216₈ (b) 119.625₁₀ (c) 101000111₂
    4. D
       (a) 5261₈ (b) 119.625₁₀ (c) 101000111₂
       Correct
    Show answerHide answer

    Answer: D

    (b) AB1₁₆ to Octal: Convert each hex digit to 4-bit binary: A=1010, B=1011, 1=0001, giving 101010110001. Regroup this binary string into sets of 3 bits counting from the right: 101 010 110 001, which reads as 5-2-6-1, so the answer is 5261₈. The option with 5216₈ comes from mixing up the order of the grouped digits when writing the final octal number — a transposition slip, not a conversion method error.

The questions come from past JAMB, WAEC and NECO papers. We use software to help write the answer options and explanations, and every answer is checked twice before it goes on the site. How we check

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