This one is a little tough to decipher. The prime factorization of 80 is 24 x 5, which means that the prime factors of 80 are 2 and 5. For them to be common, they need to be compared to another set of prime factors.
They have the prime factors 2 and 5 in common.
19 and 90 have no common prime factors.
81 and 200 have no common prime factors.
The prime factors of 36 are 2 and 3. To be common, they need to be compared to another set of prime factors.
The prime factors of 80 are 2 and 5. For them to be common, they need to be compared to another set of prime factors.
The prime factors of 18 are 2, 3, and 3. The prime factors of 90 are 2, 3, 3, and 5. The prime factors they have in common are 2, 3, and 3. Since 18 is a factor of 90, its prime factors will be the prime factors that the two numbers have in common.
Example: What are the common prime factors of 120 and 252?Find the prime factorization of each number by breaking it down into the lowest possible numbers that can be multiplied together to make the original number.120 = 2x60 = 2x2x30 = 2x2x2x15 = 2x2x2x3x5252 = 2x126 = 2x2x63 = 2x2x3x21 = 2x2x3x3x7Notice that there are 2 2's and a 3 in each factorization: the common prime factors are 2, 2, and 3.
2 and 3 are the only common prime factors
The common prime factors are 2 and 3
The prime factors of 110 are 2, 5 and 11. For them to be common, they need to be compared to another set of prime factors.
When two or more numbers have one or more of the same primes as factors, those prime factors are called common prime factors. For example, the prime factors of 6 are 2 and 3, and the prime factors of 21 are 3 and 7, so 3 is a common prime factor of 6 and 21.
There are infinitely many prime factors.