Declension table of ?dīrghasandhyatva

Neuter	Singular	Dual	Plural
Nominative	dīrghasandhyatvam	dīrghasandhyatve	dīrghasandhyatvāni
Vocative	dīrghasandhyatva	dīrghasandhyatve	dīrghasandhyatvāni
Accusative	dīrghasandhyatvam	dīrghasandhyatve	dīrghasandhyatvāni
Instrumental	dīrghasandhyatvena	dīrghasandhyatvābhyām	dīrghasandhyatvaiḥ
Dative	dīrghasandhyatvāya	dīrghasandhyatvābhyām	dīrghasandhyatvebhyaḥ
Ablative	dīrghasandhyatvāt	dīrghasandhyatvābhyām	dīrghasandhyatvebhyaḥ
Genitive	dīrghasandhyatvasya	dīrghasandhyatvayoḥ	dīrghasandhyatvānām
Locative	dīrghasandhyatve	dīrghasandhyatvayoḥ	dīrghasandhyatveṣu

Compound dīrghasandhyatva -

Adverb -dīrghasandhyatvam -dīrghasandhyatvāt