dyāv-ābhūmyor yad antaram
koṭyaḥ syuḥ pañca-viṁśatiḥ
The word koṭi means ten million, and a yojana is eight miles. The diameter of the universe is fifty koṭi yojanas (four billion miles). Therefore, since the sun is in the middle of the universe, the distance between the sun and the edge of the universe is calculated to be twenty-five koṭi yojanas (two billion miles).