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S5 ICT Programming Loops, Paper 3: accumulators, digits and patterns
S5 ICT Programming Loops, Paper 3: accumulators, digits and patterns
Paper 3 works through a decrementing while loop of five rounds, the sum 1 to 100 as 5050, five factorial as 120, ten multiples of 3 up to 30, a star pattern of four lines and ten stars, a digit sum of 22 from 4729, ten doublings to reach 1024, a reversed string and fifteen nested dashes.
Reminders A while test must move towards failing, an accumulator starts at 0, and nested iterations multiply.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 25 |
| Difficulty mix | Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1 |
| Chapter | Chapter: S5 ICT: Programming Loops in Python |
| Level | S5 |
02 Questions (10 items)
- FoundationAfter `n = 5`, how many times does `while n > 0: n -= 1` run?
- Foundation`total = 0` then `for i in range(1, 101): total += i`. What is total?
- Foundation`f = 1` then `for i in range(1, 6): f *= i`. What is f?
- FoundationHow many numbers does `for i in range(3, 31, 3)` print?
- Intermediate`for i in range(1, 5): print(“*” * i)` prints how many lines and how many stars in total?
- Intermediate`s = 0; n = 4729` then `while n > 0: s += n % 10; n //= 10`. What is s?
- Intermediate`x = 1; c = 0` then `while x < 1000: x *= 2; c += 1`. What is c?
- ChallengeTo print PYTHON reversed as NOHTYP, what is the shortest statement?
- Challenge`for i in range(3): for j in range(5): print(“-“, end=””)` prints how many dashes in total?
- Error redoError repair: a student wrote `i = 10` then `while i > 0: print(i)` and it never stops. What is missing?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | 5 times | Starting at 5 and subtracting 1 each round, the loop runs for 5, 4, 3, 2 and 1, then n reaches 0 and the test fails. |
| 2 | 5050 | Adding 1 to 100 is 100 times 101 divided by 2, which gives 5050. |
| 3 | 120 | This multiplies 1 to 5, which is five factorial, equal to 120. |
| 4 | 10 numbers | Starting at 3 and adding 3 each step gives 3, 6, 9 up to 30, ten numbers in all. |
| 5 | 4 lines, 10 stars | There are 4 lines with 1, 2, 3 and 4 stars, which add up to 10. |
| 6 | 22 | Each round takes the last digit and drops it, giving 9, 2, 7 and 4, which add to 22. |
| 7 | 10 (x becomes 1024) | Doubling from 1 reaches 1024 after 10 multiplications, and 1024 is no longer below 1000. |
| 8 | print(“PYTHON”[::-1]) | A slice step of minus 1 walks the string backwards in one line, with no loop needed. |
| 9 | 15 | The outer loop runs 3 times and the inner loop prints 5 dashes each time, so 3 times 5 is 15. |
| 10 | Decreasing i inside the loop (i -= 1) | A condition that never fails loops forever, so the body must change something that moves the test towards failing. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
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