on *TEXT:!lb2kg*:#: {
if ($2 isnum) {
    msg $chan $2 Lbs is about equal to $calc($2 / 2.2) Kg(s).
  }
}
on *TEXT:!kg2lb*:#: {
if ($2 isnum) {
    msg $chan $2 Kg(s) is about equal to $calc($2 * 2.2) Lb(s).
  }
}