Declension table of ?gāyatrīmantra

Masculine	Singular	Dual	Plural
Nominative	gāyatrīmantraḥ	gāyatrīmantrau	gāyatrīmantrāḥ
Vocative	gāyatrīmantra	gāyatrīmantrau	gāyatrīmantrāḥ
Accusative	gāyatrīmantram	gāyatrīmantrau	gāyatrīmantrān
Instrumental	gāyatrīmantreṇa	gāyatrīmantrābhyām	gāyatrīmantraiḥ gāyatrīmantrebhiḥ
Dative	gāyatrīmantrāya	gāyatrīmantrābhyām	gāyatrīmantrebhyaḥ
Ablative	gāyatrīmantrāt	gāyatrīmantrābhyām	gāyatrīmantrebhyaḥ
Genitive	gāyatrīmantrasya	gāyatrīmantrayoḥ	gāyatrīmantrāṇām
Locative	gāyatrīmantre	gāyatrīmantrayoḥ	gāyatrīmantreṣu

Compound gāyatrīmantra -

Adverb -gāyatrīmantram -gāyatrīmantrāt