Question

find all the factors of 18, 19, and 20. do they have any factors in common? explain how you can tell if some numbers have factors in common without finding the factors.
are there any common factors? select the correct choice below and, if necessary, fill in the answer box to complete your choice.
a. the numbers 18, 19, and 20 have the factor(s) \boxed{} in common.
(use a comma to separate answers as needed.)

Explanation:

Step1: Identify prime number

19 is a prime number, so its only positive factors are 1 and 19.

Step2: Check divisibility by 19

18 and 20 are not divisible by 19, so 19 cannot be a common factor.

Step3: Check universal common factor

The number 1 is a factor of every positive integer, so 1 is a common factor of 18, 19, and 20.

Answer:

A. The numbers 18, 19, and 20 have the factor(s) 1 in common.

To confirm without listing all factors: 19 is prime, so its only factors are 1 and 19. Since 19 does not divide 18 or 20, the only shared factor across all three numbers is 1, which is a factor of every integer.