The GCF is 21.
The GCF is 21.
The GCF is 21.
The GCF is 21.
The GCF is 5.
The GCF is 5.
The GCF is 1.
The GCF is 21.
The GCF is 1.
The GCF of 84 and 63 is 21
The GCF is 7.
The GCF is: 7
That unknown third number could potentially change the answer, but the GCF of 63 and 84 is 21.