The affix dhā comes after a Numeral when the sense is a change in the apportionment or distribution of substances.,
The word संख्यायाः is understood here. The word अधिकरणं means 'matter, stuff, substance'. विचालः 'change in numbers'. Thus to make one into many, or to make many into one. Thus एकं राशिं कुरु 'divide one heap into five'. अष्टधा कुरु, अनेकमेकधा कुरु ॥,