Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 1 · Basics and Panchanga
ज्योतिषमूलं पञ्चाङ्गं च
उत्पत्तिलक्षणं चैव सर्वं संक्षेपतो ब्रुवे ।एकं दश शतं चैव सहस्त्रायुतलक्षकम् ॥ १२ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 54, verse 12.
The marks of how things arise. I will tell all of this in brief. One, ten, a hundred, a thousand, ten thousand, a lakh.
Simple meaning: I will explain all this briefly. Then the places of numbers are named, from one up to a lakh.
स्वाहोरात्रचतुर्भागे दिनरात्रिदले स्मृते ।
A quarter of a planet's day-and-night, corrected, gives half its day and night. Double them for the full lengths.
भभोगोऽष्टशतीर्लिप्ताः स्वाश्विशैलोस्तथातिथेः ।
A nakshatra spans 800 minutes of arc and a tithi 720. Divide a planet's minutes by 800 to get its nakshatra.
रवींदुयोगलिप्तास्तु योगाभभोगभाजिताः ।
Add the Sun and Moon minutes and divide by 800 to get the yoga. Then find the ghatikas.