There is no GCF for those two numbers. It is already simplified.
* * * * *
GCF(83, 99) = 1
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 99.
99 - 83 = 16
GCF(83, 100) = 1. The numbers are coprime.
The GCF is 1.
The GCF is 9.
The GCF is 11.
The GCF is 11.
The GCF is 9.
The GCF is 1.