You need at least two numbers to find a GCF.
If that's 84, 126, 210 and 378, the GCF is 42.
The GCF is 6.
The GCF is 9.
The GCF is 4.
The GCF is 30.
50
The GCF is 27.
The GCF is: 1
The GCF is 1.
The GCF is 5.
The GCF is 2.
The GCF is 3.
The GCF of 125, 200 is 25.