पूरणाद् भागे तीयाद् अन्

This sutra is made only to teach accent, for the word to which अन् is added undergoes no other change of form except in accent. Thus द्विती꣡यः 5.2.54 has udatta on ती 3.1.3 but when अन् is added, the accent falls on द्वि (VI. I. 197). Thus द्वितीयो भागः = द्वि꣡तीयः 'the moiety'. Similarly तृ꣡तीयः 'the one-third'. Why do we say when 'part' is meant? Otherwise, there is no change in accent. The affix तीय always comes in forming ordinal numbers and for no other purpose, for the तीय in words like मुखतीय is not significant as it is not an affix. The employment of the word पूरण in the aphorism is useless for the purposes of this sutra. Its anuvritti, however, runs in the other sutras, and that is the only purpose that it serves here.,