Electronics Worksheet: Loops and Variables

Electronics lesson 25: Loops and variables · Set 138 · 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.🔁 x = 5
   repeat 1 time { x = x × 2 }
   What is x at the end?
2. 2.🔁 count = 4
   while (count < 16) { count = count + 2 }
   How many times does the loop run?
3. 3.🔁 x = 5
   repeat 2 times { x = x × 2 }
   What is x at the end?
4. 4.🔁 total = 0
   for i = 1 to 6 { total = total + i }
   What is total at the end?
5. 5.🔁 What does a variable do in a program? (a) joins two wires (b) measures light (c) blinks an LED (d) stores a value
6. 6.🔁 repeat 3 times { repeat 2 times { beep } }
   How many beeps are there?
7. 7.🔁 x = 1
   repeat 3 times { x = x × 2 }
   What is x at the end?
8. 8.🔁 count = 9
   repeat 4 times { count = count + 2 }
   What is count at the end?
9. 9.🔁 count = 1
   repeat 3 times { count = count + 9 }
   What is count at the end?
10. 10.🔁 repeat 6 times { repeat 3 times { beep } }
    How many beeps are there?
11. 11.🔁 x = 4
    repeat 2 times { x = x × 2 }
    What is x at the end?
12. 12.🔁 repeat 5 times { repeat 3 times { beep } }
    How many beeps are there?
13. 13.🔁 count = 7
    repeat 2 times { count = count + 6 }
    What is count at the end?
14. 14.🔁 total = 0
    for i = 1 to 5 { total = total + i }
    What is total at the end?
15. 15.🔁 count = 1
    while (count < 16) { count = count + 3 }
    How many times does the loop run?
16. 16.🔁 count = 0
    while (count < 12) { count = count + 3 }
    How many times does the loop run?
17. 17.🔁 x = 1
    repeat 2 times { x = x × 2 }
    What is x at the end?
18. 18.🔁 total = 0
    for i = 1 to 10 { total = total + i }
    What is total at the end?
19. 19.🔁 count = 0
    while (count < 4) { count = count + 2 }
    How many times does the loop run?
20. 20.🔁 repeat 5 times { repeat 2 times { beep } }
    How many beeps are there?
21. 21.🔁 count = 4
    repeat 3 times { count = count + 2 }
    What is count at the end?
22. 22.🔁 total = 0
    for i = 1 to 4 { total = total + i }
    What is total at the end?
23. 23.🔁 count = 2
    repeat 3 times { count = count + 8 }
    What is count at the end?
24. 24.🔁 count = 4
    repeat 2 times { count = count + 6 }
    What is count at the end?
25. 25.🔁 x = 3
    repeat 3 times { x = x × 2 }
    What is x at the end?
26. 26.🔁 count = 7
    repeat 8 times { count = count + 8 }
    What is count at the end?
27. 27.🔁 x = 3
    repeat 1 time { x = x × 2 }
    What is x at the end?
28. 28.🔁 count = 9
    repeat 6 times { count = count + 9 }
    What is count at the end?
29. 29.🔁 What does “count = count + 1” do? (a) adds 1 to count (b) sets count to 1 (c) prints 1 (d) takes 1 away
30. 30.🔁 total = 0
    for i = 1 to 3 { total = total + i }
    What is total at the end?
31. 31.🔁 count = 1
    while (count < 25) { count = count + 4 }
    How many times does the loop run?
32. 32.🔁 count = 3
    repeat 9 times { count = count + 10 }
    What is count at the end?
33. 33.🔁 count = 0
    while (count < 20) { count = count + 4 }
    How many times does the loop run?
34. 34.🔁 count = 0
    repeat 2 times { count = count + 4 }
    What is count at the end?
35. 35.🔁 x = 2
    repeat 1 time { x = x × 2 }
    What is x at the end?
36. 36.🔁 x = 1
    repeat 1 time { x = x × 2 }
    What is x at the end?
37. 37.🔁 total = 0
    for i = 1 to 7 { total = total + i }
    What is total at the end?
38. 38.🔁 count = 7
    repeat 2 times { count = count + 3 }
    What is count at the end?
39. 39.🔁 x = 5
    repeat 5 times { x = x × 2 }
    What is x at the end?
40. 40.🔁 repeat 2 times { repeat 4 times { beep } }
    How many beeps are there?

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