9
You list the factors of each number...
18: 2 3 3
45: 3 3 5
Then you find the largest common grouping. It this case it is 3 3 or 9.
The GCF of 18 and 27 is 9.
The GCF is 3.
The GCF is 9.
the GCF of 45 48 and 18 is 3
The GCF is 9.
The GCF is 9.
The Greatest Common Factor (GCF) of 144, 45, and 18 is 9.
The GCF is 3.
The GCF is 9.
The GCF is 3.
The GCF is 3.
If you mean 45 and 18 then the gcf is 9