We observe that A has
3 × 2 = 6 elements, B and C have 9 and 6 elements, respectively In general, an m × n matrix has the following rectangular array:
or
A = [aij]m × n, 1≤ i ≤ m, 1≤ j ≤ n   i, j ∈ N
Thus the ith  row consists of the elements ai1, ai2, ai3, , ain, while the jth column
consists of the elements a1j, a2j, a3j, , amj,
In general aij, is an element lying in the ith row and jth column