Why does range exclude the upper limit?

That design makes range(len(items)) line up with valid indexes, so it stops one short.

When should while be used instead of for?

Use for when the count is known, and while when the loop ends on a changing condition.

S5 ICT Programming Loops, Paper 1: range, while and nesting

2026-11-02

Paper 1 starts from the start, stop and step of range and works out five printed lines, a total of 55 from 1 to 10, four rounds with a step of 3 and a while loop ending at 5, then six multiples of 3, twelve nested iterations, an even sum of 2550, eight Collatz steps and a countdown leaving i at 1.

Reminders　The upper limit of range is exclusive, a while loop must eventually turn false, and nested totals multiply outer by inner.

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)

FoundationHow many lines does `for i in range(1, 6): print(i)` print?
FoundationWith `total = 0` and `for i in range(1, 11): total += i`, what is total at the end?
FoundationHow many times does `for i in range(0, 10, 3)` iterate?
Foundation`count = 0` then `while count is below 5: count += 1`. What is count when the loop ends?
IntermediateIn `for i in range(2, 21): if i % 3 == 0:`, how many times is the condition true?
IntermediateIn the nested loops `for i in range(3): for j in range(4):`, how many inner iterations in total?
Intermediate`s = 0` then `for i in range(1, 101): if i % 2 == 0: s += i`. What is s?
ChallengeStarting at n = 6, repeat halving when even and 3n + 1 when odd until n = 1. How many steps?
Challenge`for i in range(5, 0, -1): print(i)` prints how many lines, and what is i afterwards?
Error redoError repair: a student said `range(1, 5)` gives 1, 2, 3, 4, 5, five numbers. How many is it really?

03　Answers and one-line notes

#	Answer	One-line note
1	5 lines (1 to 5)	range(1, 6) starts at 1 and stops before 6, so it prints 1 to 5, five numbers in total.
2	55	Summing 1 to 10 gives 55 because range(1, 11) covers exactly the ten numbers 1 to 10.
3	4 times	A step of 3 gives 0, 3, 6 and 9; the next value 12 is past the limit, so there are 4 iterations.
4	5	The loop continues while count is below 5, so it stops once count reaches 5 and leaves 5 behind.
5	6 times	The multiples of 3 from 2 to 20 are 3, 6, 9, 12, 15 and 18, six in all.
6	12	The outer loop runs 3 times and the inner loop 4 times each round, so 3 times 4 gives 12.
7	2550	The even numbers from 1 to 100 sum to 2 plus 4 up to 100, which is 2 times 1275, giving 2550.
8	8 steps	The chain 6 to 3 to 10 to 5 to 16 to 8 to 4 to 2 to 1 needs 8 steps; this sequence is the Collatz sequence.
9	5 lines, i is 1	Counting down from 5 to 1 gives 5 lines, and Python keeps the last value after the loop, so i is 1.
10	4 (1 to 4)	The upper limit of range is exclusive, so range(1, 5) holds only 1, 2, 3 and 4.

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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