reducing the values of matrix

I have an matrix called c=[123 345 78]

where cc= c mod 251

ie cc = [123 94 78]

how to convert these values and process in terms of polynomial division which

results in Quotient and remainder in Galois Field of (2^8)

Answer 1

[Jan]

Perhaps you mean:

c = [123 345 78]
cc = mod(c, 2^8)

But this look such obvious, that I'm afraid you want something else. So please add more information by editing the question, not as answer or comment.