If the number of candidates elected at a primary election to any nonpartisan office is less than the number of persons to be elected to that office, there shall be printed on the ballot, in a group, only the names of the other candidates receiving the next highest number of votes for nomination to that office as may equal twice the number of persons remaining to be elected to that office, or a smaller number if the list of candidates is exhausted. This group shall be preceded by the designation of the office and the words “vote for ____,” the blank being filled by a number equal to the number of persons remaining to be elected to that office.