3
The GCF for 20 and 27 is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 27.
GCF for 16 & 27 = 1Prime factorization of:16 = 2 * 2 * 2 * 227 = .................3 * 3 * 3=================GCF = 1 (since the twonumbers haveno common factor except 1)