Question

Which of the following binary operation is not commutative?

• A. Addition
• B. Multiplication
• C. Subtraction
• D. None of these

Answer 1

The correct option is C

Subtraction

For a binary operation ${}^{\ast }$ to be commutative, we need a ${}^{\ast }$ b = b ${}^{\ast }$ a for all a and b.

For multiplication and addition, this is true because ab = ba and a+b = b+a. But for subtraction a-b is not equal to b-a for all a and b. So it's not commutative.