Just 1.
Factors of 20:1,2,4,5,10,20Factors of 65:1,5,13,65The common factors are 1 and 5.
13 and 20 don't have common factors, so 13/20 can't be simplified any more.
Factors of 13: 1, 13Factors of 20: 1, 2, 4, 5, 10, 20GCF (13, 20) = 1
The common factors of 13 and 39 are: 1 and 13
13 = 1 x 13, 20 = 2 x 2 x 5. There are no common factors so the LCM is the product, ie 260.
Since 13 is a factor of 39, all of its factors are common.
Since 13 is a prime number, its only positive integer factors are itself and 1. Since the number 20 shares the common factor 1, the only common factor of the numbers is 1.
The factors of 13 are 1 and 13. For them to be common, they need to be compared to another set of factors.
Well, honey, the common factors of 13 and 26 are 1 and 13. That's it, plain and simple. Not much to work with there, but hey, at least you got your answer.
The common factors of 21 and 36 are 1 and 3
13 is a prime number. The only common factors are 1 and 13.
The GCF of 143 and 169 is 13. One way to determine the common factors and greatest common factor is to find all the factors of the numbers and compare them. The factors of 143 are 1, 11, 13, and 143. The factors of 169 are 1, 13, and 169. The common factors are 1 and 13. Therefore, the greatest common factor is 13.