Electronics Worksheet: Loops and Variables

Electronics lesson 25: Loops and variables · Set 843 · 40 questions

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.

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

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