Final answer:
The greatest common factor of 2240 and 399 is 7, as determined by finding the prime factors of each number and identifying the shared prime factor.
Step-by-step explanation:
The common factor between two numbers is a number that divides both of them without leaving a remainder. To find the common factor of 2240 and 399, we need to perform a factor analysis on both numbers and find the largest number that is present in both of their factorizations. Let's begin with finding the prime factors of each number. For 2240, the prime factors are 2 × 2 × 2 × 2 × 2 × 5 × 7 (or 25 × 5 × 7). For 399, the prime factors are 3 × 7 × 19. As we can see, the only common prime factor between 2240 and 399 is 7. Therefore, the greatest common factor of 2240 and 399 is 7.