7 elements:-Find all ordered pairs of natural number whose product is 7.
All ordered pairs are $1\times 7,7\times 1$
Hence two types of matrices exists.
(i) Column matrix:If it has only one column.
Hence order of matrix=$m\times 1=7\times 1.$
(ii) Row matrix:If it has only one row.
Hence order of matrix=$1\times n=1\times 7.$