Agni Purana (Jyotisha Selections) · by Vyasa
Chapter 1 · Muhurta: Marriage, Home, Farming
ज्योतिःशास्त्रम्
शेषवाराश्च सूर्याद्या घटिकासु च पातयेत् ।पिण्डकेषु तिथिं दद्याद्धरेच्चैव चतुर्दशे ॥ १० ॥
In the full Agni Purana this is chapter 122, verse 10.
The remainders are weekdays counted from Sunday. Set the correction into the ghatikas (24-minute units). Add the tithi (moon day) to the pindas (total figures). Divide by 14.
Simple meaning: 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.
पञ्चदश तृतीये च तथा चैकादशे स्मृतम् ।
The third and eleventh are fifteen. The fourth and tenth are nineteen.
पञ्चमे नवमे चैव द्वाविंशतिरुदाहृताः ।
The fifth and ninth are twenty-two. The sixth and eighth are twenty-four.