Declension table of mantavya

Neuter	Singular	Dual	Plural
Nominative	mantavyam	mantavye	mantavyāni
Vocative	mantavya	mantavye	mantavyāni
Accusative	mantavyam	mantavye	mantavyāni
Instrumental	mantavyena	mantavyābhyām	mantavyaiḥ
Dative	mantavyāya	mantavyābhyām	mantavyebhyaḥ
Ablative	mantavyāt	mantavyābhyām	mantavyebhyaḥ
Genitive	mantavyasya	mantavyayoḥ	mantavyānām
Locative	mantavye	mantavyayoḥ	mantavyeṣu

Compound mantavya -

Adverb -mantavyam -mantavyāt