you could do

on *:TEXT:!random*:#:{ 
  if ($2) { msg # $iif($2 == number,$+($r(1,10),$r(1,10),$r(1,10)),$iif($2 == text,$+($r(a,z),$r(a,z),$r(a,z),$r(a,z)))) }
  else { msg $chan $nick Please Type either !random number or !random text }
}