The greatest common factor (GCF) of 5 and 7 is 1. This is because the only positive integer that divides both 5 and 7 without leaving a remainder is 1.
To understand this better, we can look at the factors of each number. The factors of 5 are 1 and 5, and the factors of 7 are 1 and 7. The only factor that both numbers share is 1. Since 5 and 7 are prime numbers, they do not have any other common factors.
Therefore, the GCF of 5 and 7 is 1.