Returns the greatest common divisor of two or more integers. The greatest common divisor is the largest integer that divides
into all of the argument numbers without a remainder.

The Syntax for the GCD function is: =GCD(number1,[number2],…)

Number1 is required, the other numbers are optional.

There can be from 1 to 255 numbers. If a number is not an integer the decimal portion is dropped.
If any argument is nonnumeric, the function returns a #VALUE! error.
If any argument is less than zero, the function returns a #NUM! error.
The greatest common divisor of 24 and 36 is 12. The values 2, 4, and 6 will also divide evenly into 24 and 36,
but 12 is the largest value that will divide into them evenly.

One divides into any value evenly.

A prime number such as 1, 3, 5, 7, 11, 13, 17, etc. has only itself and one as even divisors.