Group division G/N is defined if N is normal G/N = cosets of N in G. example: D3/C3 forall g,g1,g2 in G NN=N => (gN)N=gN NgN=gN g1Ng2N=g1g2N (gN)^=g^N example: C3 subset of D3 normal D3/C3= {N,bN} ~= C2 Sn/An ~= C2 forall n