The affix kṛtvasuc is added to a numeral when the repetition of such an action is to be counted.,
This is also a svartha affix. The word अभ्यावृत्तिः means \again and again or repetition\. The counting of actions belonging to the same class and having the same agent, which occur again and again is called क्रियाभ्यावृत्तिगणनम् ॥ Thus पंचवारान् भुङ्क्ते = पंचकृत्वोभुक्तं \he eats five times\. So also सप्तकृत्वः &c.
Why do we say \after a Numeral\? Observe भूरीन् वारान् भुंक्ते \he eats many times\.
Objection:- Why do we say \action\ when we know that an 'action' alone can be repeated, and not a substance or an attribute? Reply: The word क्रिया is employed in this sutra for the sake of the next sutras, into which its anuvritti flows. Thus in sutra 5.4.19, एकस्य सकृच्च when the affix does not apply to count repetition, because it is impossible for a unit to express repetition; but merely to count the \action\ only.
Why do we use the word \repetition\? The affix will not apply when merely \actions\ are counted. Thus पंचपाकाः \five cookings\, दशपाकाः &c.
Why do we use the word \counting\, when we know that a Numeral is nothing but counting ? Had the sutra been merely संख्यायाः क्रियाभ्यावृत्तौ कृत्वसुच्, there would arise this anomaly. The numerals upto ten denote only the thing numbered (संख्येय), but the numerals above those denote both the counting (संख्यान) and the thing counted (संख्येय) ॥ If गणन were not used, the affix would come only after the numeral denoting sankhyeya and not sankhyana. Thus it will apply to शतवारान् भुङ्क्ते = शतकृत्वः, but not here शतं वाराणां भुङ्क्ते; because here the word शत does not denote repetition, but merely a counting. By using the word गणन it applies to both.,