Step-by-step explanation:
Given that M is a positive integer, M + 1 is also a positive integer.
Since the difference between them is only 1, they cannot have a common factor above 1.
(For example if M is even, M + 1 must be odd and therefore they do not have a common factor 2 and so on)
Hence we conclude the GCF of M and M + 1 is 1.
