You need at least two numbers to find a GCF.
First you find the factors of 45 and 60. The Factors of 45 are:1,3,5,9,15,and 45 The Factors of 60 are:1,2,3,4,5,6,10,12,15,20,30,60 The GCF is the highest common number so the GCF is 15.
The GCF is 15.
The GCF is 12.
The GCF is 2.
The GCF is 3.
GCF: 12
The GCF is 4.
The GCF is 20.
The GCF is 6.
The GCF is 10.
The GCF is 15.
4 is the greatest common factor. The common factors are 1,2, and 4.