S={bilangan bulat}

S = {…, -3, -2, -1, 0, 1, 2, 3, …}
A = {1, 2, 3, 4, 5, 6, 7, 8, 9}
B = {2, 3, 5, 7,11, …}

A∩B = {2, 3, 5, 7}