If the number of members of a board of education of any city school district to be elected at large as fixed by section 3313.02 of the Revised Code is even, one half thereof shall be elected in the year preceding, and the remaining one half in the year following the calendar year divisible by four. If such number is odd, one half of the remainder, after diminishing the number by one, shall be elected in the year preceding, and the remaining number shall be elected in the year following the calendar year divisible by four. All members to be elected from odd-numbered subdistricts shall be elected at one election, and all members from even-numbered subdistricts shall be elected at the alternate election.