Solution:[tex]\hbox{we have given that the combination is 2 letters and 4 digits}\\\rm{so}\\\hbox{the total number of unique combination should be the product of each possibilities}\\\hbox{therefore, the possibilities is:}\\\hbox{Total unique ID'S}=26\times26\times10\times10\times10\times10;\\\hbox{It can also be written as}\\\hbox{Total unique ID'S}=26^{2}\times10^{4}\\\hbox{this is the required possibilities.}[/tex]
