Logical operator NOT

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Quick Questions

Shade in the A or B circle for each question.

1. What is the value of NOT TRUE?

A TRUE

B FALSE

2. Score is 62. What does NOT (Score >= 50) evaluate to?

A FALSE

B TRUE

3. Score is 35. What does NOT (Score >= 50) evaluate to?

A TRUE

B FALSE

4. Found is a BOOLEAN variable set to FALSE. What is NOT Found?

A FALSE

B TRUE

5. Which condition means the same as NOT (Score >= 50)?

A Score < 50

B Score <= 50

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1NOT (Score >= 50)		ATRUE when the BOOLEAN variable Found holds FALSE
2NOT Found		BIF NOT Found THEN OUTPUT "Not found" ENDIF
3NOT reverses a condition, so NOT FALSE gives TRUE		CTRUE only when Score is below 50, because NOT reverses the condition
4NOT (Age = 18) does the same job as the not-equal operator <>		DNOT (Score >= 50) is TRUE for scores below 50, so the message should be Fail, not Pass.
5IF NOT Score >= 50 THEN OUTPUT "Fail" ENDIF		EIF Age <> 18 THEN OUTPUT "Not 18" ENDIF
6IF NOT (Score >= 50) THEN OUTPUT "Pass" ENDIF		FThe condition Score >= 50 is not in brackets, so it is unclear what NOT applies to. It should be NOT (Score >= 50).

Definitions

NOT

Fill in the Blanks

Complete each line of code by filling in the missing parts.

IF ___ (Score >= 50) THEN OUTPUT "Resit needed" ENDIF

IF NOT _____ THEN OUTPUT "Keep searching" ENDIF

Same ← NOT (Age = 18) Same2 ← Age __ 18

Pass ← NOT (Score _ 50) OUTPUT Pass

Result ← NOT _____ OUTPUT Result

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A DECLARE Score : INTEGER

B DECLARE Fail : BOOLEAN

C INPUT Score

D Fail <- (Score >= 50)

E OUTPUT Fail

Question 2

A IF NOT (Age >= 18)

B OUTPUT "Minor"

C ENDIF

Question 3

A DECLARE Found : BOOLEAN

B Found <- FALSE

C OUTPUT "Searching..."

D IF Found NOT THEN

E OUTPUT "Not found"

F ENDIF

Question 4

A DECLARE Found : BOOLEAN

B Found = FALSE

C IF NOT Found THEN

D OUTPUT "Missing"

E ENDIF

Question 5

A DECLARE Answer : STRING

B INPUT Answer

C IF NOT (Answer <> "Y") THEN

D OUTPUT "Not yes"

E ENDIF

Answer Key

Logical operator NOT

Section A: Quick Questions

B — FALSE

A — FALSE

A — TRUE

B — TRUE

A — Score < 50

Section B: Match the Pairs

NOT (Score >= 50) → TRUE only when Score is below 50, because NOT reverses the condition

NOT Found → TRUE when the BOOLEAN variable Found holds FALSE

NOT reverses a condition, so NOT FALSE gives TRUE → IF NOT Found THEN OUTPUT "Not found" ENDIF

NOT (Age = 18) does the same job as the not-equal operator <> → IF Age <> 18 THEN OUTPUT "Not 18" ENDIF

IF NOT Score >= 50 THEN OUTPUT "Fail" ENDIF → The condition Score >= 50 is not in brackets, so it is unclear what NOT applies to. It should be NOT (Score >= 50).

IF NOT (Score >= 50) THEN OUTPUT "Pass" ENDIF → NOT (Score >= 50) is TRUE for scores below 50, so the message should be Fail, not Pass.

Section C: Definitions

NOT — A logical operator that reverses a condition: NOT TRUE is FALSE and NOT FALSE is TRUE. For example, NOT (Score >= 50) is TRUE only when Score is below 50.

Section D: Fill in the Blanks

IF NOT (Score >= 50) THEN
   OUTPUT "Resit needed"
ENDIF

IF NOT Found THEN
   OUTPUT "Keep searching"
ENDIF

Same ← NOT (Age = 18)
Same2 ← Age <> 18

Pass ← NOT (Score < 50)
OUTPUT Pass

Result ← NOT FALSE
OUTPUT Result

Section E: Spot the Error

D — NOT is missing. Without it, Fail is TRUE when the score is 50 or more, which is the opposite of what is wanted. It should be Fail <- NOT (Score >= 50).

A — An IF statement must have THEN after its condition. The line should be IF NOT (Age >= 18) THEN.

D — NOT is a prefix operator, so it goes before the value it reverses. The line should be IF NOT Found THEN.

B — = is a comparison, not assignment. Cambridge pseudocode assigns with <-, so the line should be Found <- FALSE.

C — NOT reverses <>, so NOT (Answer <> "Y") means the same as Answer = "Y". The message would show for a Y. Use NOT (Answer = "Y") or just Answer <> "Y".