

Transmitted message = 10001100 Received message = 11101100 Error polynomial = 01100000 
Error = ReceivedMsg XOR TransmittedMsg 


ReceivedMsg / GenPolynome = (TransmittedMsg XOR Error) / GenPolynome = (TransmittedMsg / GenPolynome) XOR (Error / GenPolynome) = 000...000 XOR (Error / GenPolynome) = Error / GenPolynome 

ReceivedMsg / GenPolynome = Error / GenPolynome !!! 
We can therefore conclude that:

Generator polynomial: 1101 (Math. notation: 1×x^{3} + 1×x^{2} + 0×x^{1} + + 1×x^{0}) N = 4 (Generator polynomial has 4 terms, or bits in "1001") 