There cannot be any such thing as a "greatest common multiple". Once you find the least common multiple of a set of numbers, you can keep adding the LCM to itself over and over again. Each new number you get will be a common multiple of your set of numbers, but each new number will always be larger than the previous. This means that you can keep adding while the number approaches infinity and you will still never find a greatest multiple.
Multiples of 26 include 26, 52, 78 and 104. For them to be common, they need to be compared to another set of multiples.
The LCM is 26.
Multiples of 13 include 13, 26, 39 and so on. For them to be common, they need to be compared to another set of multiples.
The LCM is 156.
There is an infinite number of common multiples for 26 and 24. A common multiple of any two or more numbers is any number into which each of two or more numbers can be divided evenly (zero remainder). However, the least or lowest common multiple of 26 and 24 is 312.
26 = 26, 52, 78 52 = 52, 104, 156
624.
Any multiple of 416.
Any multiple of 234.
Multiples of 26 include 26, 52, 78, 104, 130 and so on. You need at least two numbers to find a GCF.
Since 26 is a multiple of 2, it is automatically the LCM of this problem.
1066, 2132, 3198