Question 638253
The bottom and the top surfaces are both
{{{24 }}} x {{{ 18 }}}
Both  sides are {{{ 18 }}} x {{{ 6 }}}
Both the front and the back are {{{ 24 }}} x {{{ 6 }}}
So I have:
Total surface = {{{ 2*24*18 + 2*18*6 + 2*24*6 }}}
Total Surface = {{{ 864 + 216 + 288 }}}
Total Surface = 1368 cm2