9m x 10m x 30m x 9m

$${\mathtt{9}}{m}{\mathtt{\,\times\,}}{\mathtt{10}}{m}{\mathtt{\,\times\,}}{\mathtt{30}}{m}{\mathtt{\,\times\,}}{\mathtt{9}}{m} = {\mathtt{24\,300}}\left[{m}{\mathtt{\,\times\,}}{m}{\mathtt{\,\times\,}}{m}{\mathtt{\,\times\,}}{m}\right]$$  = $$24300[m^4]$$

81*300=24300m