IGCSE Computer Science Paper 2 Word Scramble: 8.1b Sequence, Selection and Iteration (Modules 379–388)
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Word scramble
Unscramble the letters and write each key term on the line.
1
POTTUU NOUTC * 7
Uses the FOR counter inside the loop body. Count holds a new value on each repeat, so this outputs a times table. Never change Count inside the loop; after the loop it keeps its last value.
2
LEWHI ENMBUR <> 0 OD
A pre-condition loop: the condition is tested before every repeat, so the body may run zero times. The loop keeps going while the condition is TRUE and is closed by ENDWHILE.
3
HWLIE MBRENU <> -1 OD
Loop that repeats until the user types a rogue (sentinel) value such as -1. INPUT before the loop and again at the end of the body; the rogue value is not counted or totalled.
4
AERETP TNLUI
A post-condition loop: the body runs first, then UNTIL tests the condition. It always runs at least once and stops when the condition is TRUE. There is no ENDREPEAT.
5
LTIUN X >= 01
Reverses WHILE X < 10. WHILE loops while TRUE, UNTIL stops when TRUE, so flip the condition. REPEAT also runs its body once before the first test.
6
OFR, LIWEH RO PEAETR
Choose FOR when the number of repeats is known, WHILE when the loop may run zero times, and REPEAT...UNTIL when the loop must run at least once.
7
OATTL <- OTLAT + MBEUNR
Adds each new value to the running total inside a loop. Set Total <- 0 before the loop starts, then OUTPUT Total after the loop ends.
8
OUNCT <- TOCUN + 1
Adds 1 to the counter each time the thing being counted happens. Set Count <- 0 before the loop, and put this inside the loop (inside an IF to count only some values).
9
RGAEVEA <- OTATL / NCOTU
After the loop ends, divide the total by the count to get the mean. Check that Count > 0 first, so the program never divides by zero.
10
NTUIL KAMR >= 0 DNA RKAM <= 001
Ends a REPEAT loop only when Mark is valid (0 to 100). Input is asked again until it passes this range check, so the program only continues with valid data.
Answer Key
IGCSE Computer Science Paper 2 · Modules 379–388
1POTTUU NOUTC * 7 → OUTPUT Count * 7 — Uses the FOR counter inside the loop body. Count holds a new value on each repeat, so this outputs a times table. Never change Count inside the loop; after the loop it keeps its last value.
2LEWHI ENMBUR <> 0 OD → WHILE Number <> 0 DO — A pre-condition loop: the condition is tested before every repeat, so the body may run zero times. The loop keeps going while the condition is TRUE and is closed by ENDWHILE.
3HWLIE MBRENU <> -1 OD → WHILE Number <> -1 DO — Loop that repeats until the user types a rogue (sentinel) value such as -1. INPUT before the loop and again at the end of the body; the rogue value is not counted or totalled.
4AERETP TNLUI → REPEAT UNTIL — A post-condition loop: the body runs first, then UNTIL tests the condition. It always runs at least once and stops when the condition is TRUE. There is no ENDREPEAT.
5LTIUN X >= 01 → UNTIL X >= 10 — Reverses WHILE X < 10. WHILE loops while TRUE, UNTIL stops when TRUE, so flip the condition. REPEAT also runs its body once before the first test.
6OFR, LIWEH RO PEAETR → FOR, WHILE or REPEAT — Choose FOR when the number of repeats is known, WHILE when the loop may run zero times, and REPEAT...UNTIL when the loop must run at least once.
7OATTL <- OTLAT + MBEUNR → Total <- Total + Number — Adds each new value to the running total inside a loop. Set Total <- 0 before the loop starts, then OUTPUT Total after the loop ends.
8OUNCT <- TOCUN + 1 → Count <- Count + 1 — Adds 1 to the counter each time the thing being counted happens. Set Count <- 0 before the loop, and put this inside the loop (inside an IF to count only some values).
9RGAEVEA <- OTATL / NCOTU → Average <- Total / Count — After the loop ends, divide the total by the count to get the mean. Check that Count > 0 first, so the program never divides by zero.
10NTUIL KAMR >= 0 DNA RKAM <= 001 → UNTIL Mark >= 0 AND Mark <= 100 — Ends a REPEAT loop only when Mark is valid (0 to 100). Input is asked again until it passes this range check, so the program only continues with valid data.