Definition:Greatest Common Divisor/Also known as

Definition
The greatest common divisor is also known as the highest common factor (abbreviated HCF or hcf) and written $\operatorname {hcf} \set {a, b}$ or $\operatorname {hcf} \tuple {a, b}$.

Alternatively, $\gcd \set {a, b}$ is written in some texts as $\tuple {a, b}$, but this notation can cause confusion with ordered pairs.

The notation $\gcd \tuple {a, b}$ is also seen, but the set notation, although a little more cumbersome, can be argued to be preferable.

The archaic term greatest common measure can also be found, mainly in such as.