The factor pairs for 21 are1 x 21 and 3 x 7
21 and 42
The GCF is 7.
21 = 1 x 21, 3 x 7, 7 x 3, 21 x 1
17
The factors of 84 are: 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84 The factors of 105 are: 1, 3, 5, 7, 15, 21, 35, 105 The common factors are: 1, 3, 7, 21 The Greatest Common Factor: GCF = 21
(21,1)(7,3) (42,1)(21,2)(14,3)(7,6) Since 21 is a factor of 42, all the factors of 21 will be included in the factor pairs of 42.
I suggest factoring each pair of numbers, and checking whether they have, or don't have, common factors. A pair of numbers is said to be "relatively prime" if they have no common factors (their greatest common factor is 1). For larger numbers, Euclid's algorithm could be used, but for such small numbers, factoring is probably faster.
The factors of 21 are: 1,3,7, and 21.
The factors of 21 are 1,3,7, and 21. The factors of 70 are 1,2,5,7,14,35, and 70.
The factors of 21 are 1, 3, 7, and 21
yesThe factors 10 and 6 are a factor pair of 60.
The factors of 21 are 1,3,7, and 21. The factors of 70 are 1,2,5,7,14,35, and 70 The common factors of 21 and 70 are 1 and 7.