Agni Purana (Jyotisha Selections) · by Vyasa
Chapter 1 · Muhurta: Marriage, Home, Farming
ज्योतिःशास्त्रम्
सप्तविंशतिशेषस्तु ध्रुवो नक्षत्रयोगयोः ।मासि मासि क्षिपेद्वारं द्वात्रिंशद्घटिकास्तिथौ ॥ ८ ॥
In the full Agni Purana this is chapter 122, verse 8.
The remainder by 27 is the starting figure for the star and the yoga (Sun-Moon yoga of the almanac). Each month add one weekday, and 32 ghatikas (24-minute units) to the tithi (moon day).
Simple meaning: The remainder by twenty-seven starts the star count. Each month adds one weekday and thirty-two time units.
द्वे पिण्डे द्वे च नक्षत्रे नाड्य एकादश ह्यृणे ।
Each month the figures gain two, two and eleven. Add the moon day and divide by seven for the weekday.
शेषवाराश्च सूर्याद्या घटिकासु च पातयेत् ।
The remainder gives the weekday from Sunday. Add the moon day to the Moon's figure and divide by fourteen.
ऋणं धनं धनमृणं क्रमाज्ज्ञेयं चतुर्दश ।
The fourteen places go minus, plus, plus, minus. The first and thirteenth are five, the second and twelfth ten.