Surya Siddhanta
खचतुष्कसमुद्राष्टकुपञ्च रविमासकाः।(५१८४००००) भवन्ति भोदया भानुभगणैर् ऊनिताः क्वहाः ॥
There are 51,840,000 Solar months in a great yuga, and the terrestrial days are the sidereal days diminished by the Sun's revolutions.
english translation
khacatuSkasamudrASTakupaJca ravimAsakAH।(51840000) bhavanti bhodayA bhAnubhagaNair UnitAH kvahAH ॥
hk transliteration by Sanscript