Declension table of ?cartavya

Neuter	Singular	Dual	Plural
Nominative	cartavyam	cartavye	cartavyāni
Vocative	cartavya	cartavye	cartavyāni
Accusative	cartavyam	cartavye	cartavyāni
Instrumental	cartavyena	cartavyābhyām	cartavyaiḥ
Dative	cartavyāya	cartavyābhyām	cartavyebhyaḥ
Ablative	cartavyāt	cartavyābhyām	cartavyebhyaḥ
Genitive	cartavyasya	cartavyayoḥ	cartavyānām
Locative	cartavye	cartavyayoḥ	cartavyeṣu

Compound cartavya -

Adverb -cartavyam -cartavyāt