For sets A,BA, BA,B: A×B={(a,b):a∈A, b∈B}A \times B = \{(a, b) : a \in A,\, b \in B\}A×B={(a,b):a∈A,b∈B}. ∣A×B∣=∣A∣⋅∣B∣|A \times B| = |A| \cdot |B|∣A×B∣=∣A∣⋅∣B∣.