Standards of Weights and Measures Act, 1976
13. Base unit of numeration. -
(1) The base unit of numeration shall be the unit of the international form of Indian numerals.
(2) Every numeration shall be made in accordance with the decimal system.
(3) The decimal multiples and sub-multiples of the numerals shall be of such denominations and be written in such manner as the Central Government may, after previous publication, specify by rules made in this behalf:
Provided that no such rule shall be made before the expiry of six months from the date on which the draft of the proposed rules was first published in the Official Gazette.