Yuga-Vibhāga and Kāla-Pramāṇa
Measures of Time and the Four Yugas
शतानि त्रीणि मासानां षष्ट्या चाप्यधिकानि वै / पित्र्यः संवत्सरो ह्येष मानुषेण विभाव्यते
śatāni trīṇi māsānāṃ ṣaṣṭyā cāpyadhikāni vai / pitryaḥ saṃvatsaro hyeṣa mānuṣeṇa vibhāvyate
Three hundred months, and sixty more—three hundred and sixty in all—are understood, by human reckoning, to be one year of the Pitṛs.