Whenever the board of county commissioners of any county deems it necessary, the board may order the register of deeds to furnish for the use of the county, in addition to other records and indexes required by law, a numerical index containing the name of the instrument, the name of the grantor, the name of the grantee, a brief description of the property and the volume and page in which each instrument indexed is recorded. A numerical index required under this section may be kept in bound paper books or in another manner authorized by statute.