1 and 28, 2 and 14, 4 and 7.
6 (-7)x(-4) (7)x(4) (1)x(28) (-1)x(-28) (2)x(14) (-2)x(-14)
14 and 21, and 21 and 28 are the number pairs between 15 and 30 that have 7 as their greatest common factor.
The factor pairs of 51 are (1,51) and (17,3)
The difference is between factor pairs and distinct factors. With square numbers, one of the factor pairs will be the same number twice. When listing the distinct factors, that number is only listed once.
The factor pairs of 28 are :28,114,27,4
The factor pairs of 28 are 1*28, 2*14, and 4*7
There are 3 factor pairs of 28. 28 = 1 x 28 28 = 2 x 14 28 = 4 x 7
28 has three factor pairs which are:28 = 1 x 2828 = 2 x 1428 = 4 x 7
Its factors are only itself and one because 7 is a prime number
28,114,27,4
1 & 28, 2 & 14, 4 & 7
1,282,144,7-1,-28-2,-14-4,-7
1, 28 2, 14 4, 7
1 and 28 2 and 14 4 and 7
The factor pairs of 112 are 1*112, 2*56, 4*28, 7*16, and 8*14
The factor pairs of 56 are: 1, 56; 2, 28; 4, 14; 7, 8 Therefore, if you exclude itself and 1, there are three factor pairs, but if you include itself and 1, there are four factor pairs.