Pāṇini sūtras

After a numeral, the first vowel of a word denoting mass in its widest sense (with the exception of śāṇa) gets the Vṛiddhi before a Taddhita affix having an indicatory ñ, ṇ or k, when the word so formed does not mean a Name.

1. parimāṇa+antasyaपरिमाण+अन्तस्य

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   pप्	parimāṇaपरिमाण	parimāṇaपरिमाण	measure	parimāṇपरिमाण् + plus aअ
   aअ	antaअन्त	antasyaअन्तस्य	end	antअन्त् + plus asyaअस्य

2. a+saṃjñā+śāṇayoḥअ+संज्ञा+शाणयोः

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   aअ	aअ	aअ	not	aअ
   sस्	saṃjñसंज्ञ्	saṃjñāसंज्ञा	name	saṃjñसंज्ञ् + plus āआ
   śश्	śāṇaशाण	śāṇayoḥशाणयोः	śāṇa [word]शाण [wओर्द्]	śāṇशाण् + plus ayoḥअयोः

Anuvṛtti

1. uttara+padasyaउत्तर+पदस्य 7·3·10

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   uउ	uttaraउत्तर	uttaraउत्तर	following	uttarउत्तर् + plus aअ
   pप्	padaपद	padasyaपदस्य	word	padपद् + plus asyaअस्य

2. saṅkhyāyāḥसङ्ख्यायाः 7·3·15

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   sस्	saṃkhyāसंख्या	saṅkhyāyāḥसङ्ख्यायाः	numeral	saṃkhyसंख्य् + plus āyआय्