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Electronics Worksheet: Loops and Variables

Electronics lesson 25: Loops and variables · Set 4 · 40 questions
TalentJR

Remember (Trace every pass): count = count + k adds k each time round; after n rounds: start + n × k. A loop inside a loop runs outer × inner times. while (condition) repeats until the condition is false — count the rounds as you trace.

NameDateTime takenScore ___ / 40
  1. 1.🔁 x = 5
    repeat 1 time { x = x × 2 }
    What is x at the end?
  2. 2.🔁 repeat 2 times { repeat 2 times { beep } }
    How many beeps are there?
  3. 3.🔁 total = 0
    for i = 1 to 6 { total = total + i }
    What is total at the end?
  4. 4.🔁 repeat 2 times { repeat 6 times { beep } }
    How many beeps are there?
  5. 5.🔁 What does “count = count + 1” do? (a) sets count to 1 (b) adds 1 to count (c) takes 1 away (d) prints 1
  6. 6.🔁 repeat 5 times { repeat 2 times { beep } }
    How many beeps are there?
  7. 7.🔁 total = 0
    for i = 1 to 7 { total = total + i }
    What is total at the end?
  8. 8.🔁 count = 1
    while (count < 41) { count = count + 5 }
    How many times does the loop run?
  9. 9.🔁 x = 4
    repeat 3 times { x = x × 2 }
    What is x at the end?
  10. 10.🔁 count = 1
    while (count < 7) { count = count + 2 }
    How many times does the loop run?
  11. 11.🔁 count = 2
    repeat 8 times { count = count + 6 }
    What is count at the end?
  12. 12.🔁 count = 3
    repeat 6 times { count = count + 9 }
    What is count at the end?
  13. 13.🔁 count = 1
    repeat 4 times { count = count + 7 }
    What is count at the end?
  14. 14.🔁 What does a variable do in a program? (a) joins two wires (b) measures light (c) stores a value (d) blinks an LED
  15. 15.🔁 count = 1
    repeat 8 times { count = count + 5 }
    What is count at the end?
  16. 16.🔁 repeat 5 times { repeat 6 times { beep } }
    How many beeps are there?
  17. 17.🔁 x = 3
    repeat 3 times { x = x × 2 }
    What is x at the end?
  18. 18.🔁 count = 2
    repeat 9 times { count = count + 2 }
    What is count at the end?
  19. 19.🔁 x = 3
    repeat 1 time { x = x × 2 }
    What is x at the end?
  20. 20.🔁 x = 5
    repeat 4 times { x = x × 2 }
    What is x at the end?
  21. 21.🔁 x = 4
    repeat 5 times { x = x × 2 }
    What is x at the end?
  22. 22.🔁 count = 3
    while (count < 11) { count = count + 2 }
    How many times does the loop run?
  23. 23.🔁 count = 3
    while (count < 15) { count = count + 3 }
    How many times does the loop run?
  24. 24.🔁 repeat 2 times { repeat 3 times { beep } }
    How many beeps are there?
  25. 25.🔁 count = 5
    while (count < 13) { count = count + 2 }
    How many times does the loop run?
  26. 26.🔁 x = 1
    repeat 4 times { x = x × 2 }
    What is x at the end?
  27. 27.🔁 count = 0
    while (count < 40) { count = count + 5 }
    How many times does the loop run?
  28. 28.🔁 count = 2
    while (count < 26) { count = count + 3 }
    How many times does the loop run?
  29. 29.🔁 repeat 5 times { repeat 4 times { beep } }
    How many beeps are there?
  30. 30.🔁 total = 0
    for i = 1 to 3 { total = total + i }
    What is total at the end?
  31. 31.🔁 x = 4
    repeat 4 times { x = x × 2 }
    What is x at the end?
  32. 32.🔁 total = 0
    for i = 1 to 12 { total = total + i }
    What is total at the end?
  33. 33.🔁 count = 9
    repeat 4 times { count = count + 5 }
    What is count at the end?
  34. 34.🔁 count = 8
    repeat 10 times { count = count + 5 }
    What is count at the end?
  35. 35.🔁 count = 4
    repeat 3 times { count = count + 3 }
    What is count at the end?
  36. 36.🔁 count = 0
    while (count < 12) { count = count + 3 }
    How many times does the loop run?
  37. 37.🔁 count = 0
    while (count < 6) { count = count + 3 }
    How many times does the loop run?
  38. 38.🔁 count = 2
    while (count < 6) { count = count + 2 }
    How many times does the loop run?
  39. 39.🔁 count = 0
    repeat 10 times { count = count + 4 }
    What is count at the end?
  40. 40.🔁 total = 0
    for i = 1 to 5 { total = total + i }
    What is total at the end?

Answer key

  1. 10
  2. 4
  3. 21
  4. 12
  5. adds 1 to count
  6. 10
  7. 28
  8. 8
  9. 32
  10. 3
  11. 50
  12. 57
  13. 29
  14. stores a value
  15. 41
  16. 30
  17. 24
  18. 20
  19. 6
  20. 80
  21. 128
  22. 4
  23. 4
  24. 6
  25. 4
  26. 16
  27. 8
  28. 8
  29. 20
  30. 6
  31. 64
  32. 78
  33. 29
  34. 58
  35. 13
  36. 4
  37. 2
  38. 2
  39. 40
  40. 15

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