Brihat Parashara Hora Shastra
वह्निभाज्जन्मभं यावद् या संख्या नवतष्टिता । शेषाद्दशाधिपो ज्ञेयस्तमारभ्य दशां नयेत् ॥ १३॥
Thus, if the Nakshatras from Kritika to the Janm Nakshatr are divided by nine, the remainder will signify the Lord of the commencing Dasha.
english translation
vahnibhAjjanmabhaM yAvad yA saMkhyA navataSTitA । zeSAddazAdhipo jJeyastamArabhya dazAM nayet ॥ 13॥
hk transliteration by Sanscript