Express the volume of each cube as a monomial

[tex]\\ \rm\longmapsto Volume[/tex]
[tex]\\ \rm\longmapsto (side)^3[/tex]
[tex]\\ \rm\longmapsto (7m^6n^9)^3[/tex]
[tex]\\ \rm\longmapsto 7^3m^{18}n^{27}[/tex]
[tex]\\ \rm\longmapsto 343m^{18}n^{27}[/tex]