No, the GCF is the lesser of the numbers.
There is no greatest common multiples for whatever common multiple is claimed to be the greatest the lowest common multiple of the numbers (in this case 15) can be added to get an even greater common multiple.
In that scenario, the GCF is the lesser of the numbers. The LCM is the greater.
The GCF of the numbers is the greatest common factor no matter what their relationship is. When one number is a multiple of another number, the GCF is the smaller number.
There can never be a greatest common multiple of one number for two reasons:"Common" refers to a multiple that is common to two or more numbers. You cannot have a multiple that is common, but only to one number.If X is the greatest common multiple of a set of numbers, then any multiple of X will also be a common multiple of each member of the set and it will be greater than X. And then, any multiple of this number will be a multiple of each member of the set and will be greater still. And then ...
The answer is sometimes - when the multiple in question is 1.
There is no greatest common multiple of any integers as whatever number is said to be it, the lowest common multiple of the numbers can be added to get an even greater common multiple. If you mean least common multiple (the lowest (positive) integer that can be divided by the numbers without a remainder), the answer is 312. If you mean the greatest common factor (the greatest (positive) integer that can divide into the numbers without any remainder). the answer is 4.
There can be no such number. Suppose x is the least common multiple (LCM) of these numbers. Then 2*LCM is also a common multiple and is greater. And then 3*LCM is a common multiple and greater still. And so on, for ever.
The greatest common multiple of any set of integers is infinite.
The greatest common multiple of any set of numbers is infinite. The greatest common multiple of any set of numbers will never be one.
The greatest common multiple of any two numbers is infinite.
There is no "greatest common multiple" of any two numbers. Whatever their product is, it can be multiplied by any positive integer to yield an even greater number that is also a multiple of the first two. Thus, the number of multiples is infinite.