Surya Siddhanta
युगानाम् सप्ततिः सैका मन्वन्तरम् इहोच्यते। कृताब्दसम्ख्यास् तस्यान्ते सन्धिः प्रोक्तो जलप्लवः ॥
(According to the technicality of time called Múrta,) 71 great yugas (containing 306,720,000 solar years) constitute a Manwantara (a period from the beginning of a Manu to its end) and at the end of it, 1,728,000 the whole number of the (solar) years of the Krịta, is called its Sandhi; and it is the time when a universal deluge happens.
english translation
yugAnAm saptatiH saikA manvantaram ihocyate। kRtAbdasamkhyAs tasyAnte sandhiH prokto jalaplavaH ॥
hk transliteration by Sanscript