Which of the following is a Boolean operator ?
2023
Which of the following is a Boolean operator ?
Answer: A. OR — ConceptA Boolean operator is an operation defined on truth values — quantities that can take only the two values 0 (false) and 1 (true) — and whose result is…
- A.
OR
- B.
Add
- C.
Subtract
- D.
Multiply
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Correct answer: A
Concept
A Boolean operator is an operation defined on truth values — quantities that can take only the two values 0 (false) and 1 (true) — and whose result is itself a truth value. Boolean algebra is built on exactly three such basic operators: AND, OR and NOT. An arithmetic operator is a different kind of object: it acts on numeric magnitudes and returns a number, whose size depends on how large the inputs are.
Application
Apply that test to each operation named in the list. OR is defined on truth values, and its complete behaviour is fixed by a truth table:
A | B | A OR B |
|---|---|---|
0 | 0 | 0 |
0 | 1 | 1 |
1 | 0 | 1 |
1 | 1 | 1 |
Every entry in the result column is again 0 or 1, so OR maps truth values to a truth value — exactly what the definition of a Boolean operator requires.
Add, Subtract and Multiply are arithmetic operations. They act on numeric magnitudes and return numbers whose size tracks the inputs: 1 + 1 = 2, 0 − 1 = −1, 3 × 4 = 12. None of these results is restricted to the two truth values, so none of these three operations is a Boolean operator.
Cross-check: the “+” and “·” notation
This is where the question is most often misread. In Boolean algebra the OR operation is conventionally written with a plus sign (A + B) and the AND operation with a dot (A · B), and those two operations are sometimes called Boolean addition and Boolean multiplication. That notation is borrowed shorthand, not arithmetic — in Boolean algebra 1 + 1 = 1, while in ordinary arithmetic 1 + 1 = 2. Those Boolean readings exist only while the qualifier “Boolean” is attached: unqualified, “Add” and “Multiply” name the ordinary arithmetic operations. The list also offers “Subtract”, which has no Boolean counterpart at all — so the list is a set of arithmetic operation names with a single logical operator placed among them. The plus symbol appearing in Boolean expressions therefore does not turn the arithmetic operation “Add” into a Boolean operator, and the three basic Boolean operators remain AND, OR and NOT.
Result: of the four operations listed, OR is the Boolean operator.