Upgrading from:

Algebra`FiniteFields`

The functionality of Algebra`FiniteFields` is now available in the newly created Finite Fields Package.

To access functionality from the new Finite Fields Package, load FiniteFields`:

Version 5.2 << Algebra`FiniteFields`;
GF[7][{4}] + GF[7][{5}]

Find the number of elements in the field:

Version 5.2 << Algebra`FiniteFields`;
FieldSize[GF[7]]