Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 2 · Signs, Planets, Birth
जातकम् १
तदंशः स्वाग्नयो भक्ता लब्धोनोभूर्गुणो भवेत् ।यदैकाल्यं तदास्यांशाः स्वाग्र्याप्तोना च भूर्गुणः ॥ १३१ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 55, verse 131.
Divide its degrees by 30. Take the result away from 1: that is the multiplier. If it is less than one sign, divide its degrees by 30. One less that result is the multiplier.
Simple meaning: A multiplier is worked out by dividing parts by thirty.
सौम्यस्यार्द्धेन पापस्य समग्रेणेति निश्चयः ।
A good planet is cut by half and a bad planet by the whole amount.
आयुरंशकलाभक्ताद्विंशत्याब्दा इनाहतम् ।
The lifespan in minutes is divided to give years, months and days.
लग्नायुरंशास्त्रिगुणा दिग्भक्ता स्युः समास्ततः ।
The rising sign's parts are turned into years and months.