Declension table of ?ṣaṣṭisaṃvatsara

Masculine	Singular	Dual	Plural
Nominative	ṣaṣṭisaṃvatsaraḥ	ṣaṣṭisaṃvatsarau	ṣaṣṭisaṃvatsarāḥ
Vocative	ṣaṣṭisaṃvatsara	ṣaṣṭisaṃvatsarau	ṣaṣṭisaṃvatsarāḥ
Accusative	ṣaṣṭisaṃvatsaram	ṣaṣṭisaṃvatsarau	ṣaṣṭisaṃvatsarān
Instrumental	ṣaṣṭisaṃvatsareṇa	ṣaṣṭisaṃvatsarābhyām	ṣaṣṭisaṃvatsaraiḥ ṣaṣṭisaṃvatsarebhiḥ
Dative	ṣaṣṭisaṃvatsarāya	ṣaṣṭisaṃvatsarābhyām	ṣaṣṭisaṃvatsarebhyaḥ
Ablative	ṣaṣṭisaṃvatsarāt	ṣaṣṭisaṃvatsarābhyām	ṣaṣṭisaṃvatsarebhyaḥ
Genitive	ṣaṣṭisaṃvatsarasya	ṣaṣṭisaṃvatsarayoḥ	ṣaṣṭisaṃvatsarāṇām
Locative	ṣaṣṭisaṃvatsare	ṣaṣṭisaṃvatsarayoḥ	ṣaṣṭisaṃvatsareṣu

Compound ṣaṣṭisaṃvatsara -

Adverb -ṣaṣṭisaṃvatsaram -ṣaṣṭisaṃvatsarāt