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
13 = 1 x 13, 20 = 2 x 2 x 5. There are no common factors so the LCM is the product, ie 260.
The common factors of 13 and 39 are: 1 and 13
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.
Since 13 is a factor of 39, all of its factors are common.
The factors of 13 are 1 and 13. For them to be common, they need to be compared to another set of factors.
The factors of 13 are 1, 13 The factors of 26 are 1, 2, 13, 26 The common factors of 13 and 26 are 1 and 13. The common factors are: 1, 13
The common factors of 21 and 36 are 1 and 3
13 is a prime number. The only common factors are 1 and 13.
If that's 5/12, 10/13 and 7/9, the LCD is 468.