54 = 1 x 54, 2 x 27, 3 x 18, 6 x 9
To find this, you first have to split the numbers into their prime factors: 18 = 2x3x3 54 = 2x3x3x3 The next step is to identify any common prime factors. In this case both numbers have a 2 and two 3s as prime factors. Multiply these together gives you: 2x3x3 = 18 Therefore the HCF of 18 and 54 is 18.
In order to find common factors you need two or more numbers. However, the factors of 54 (at least 2 numbers that can be multiplied evenly, or with no remainder, into 54) are: 1,2,3,6,9,18,27, and 54.
1, 2, 3, 6, 9, 18, 27, 54 | 1 x 54, 2 x 27, 3 x 18, 6 x 9
23, 31
54 x 2=108
The numbers are: 9 and -6
-29
-6 and -9
There are 4 of them which are 2*3*3*3 = 54
-69
93
9 and 6 but subtract not add
1209
-79
-51
-28.87043 and 1.87043 (to 5 dp)