Introduction section of Mahabharata details about total number of verses.
Vyasa executed the compilation of the Bharata, exclusive of the episodes originally in twenty-four thousand verses; and so much only is called by the learned as the Bharata. Afterwards, he composed an epitome in one hundred and fifty verses, consisting of the introduction with the chapter of contents. This he first taught to his son Suka; and afterwards he gave it to others of his disciples who were possessed of the same qualifications. After that he executed another compilation, consisting of six hundred thousand verses. Of those, thirty hundred thousand are known in the world of the Devas; fifteen hundred thousand in the world of the Pitris: fourteen hundred thousand among the Gandharvas, and one hundred thousand in the regions of mankind. Narada recited them to the Devas, Devala to the Pitris, and Suka published them to the Gandharvas, Yakshas, and Rakshasas: and in this world they were recited by Vaisampayana, one of the disciples of Vyasa, a man of just principles and the first among all those acquainted with the Vedas. Know that I, Sauti, have also repeated one hundred thousand verses.
So, total 600,000 verses. Of which 100,000 for mankind. This leaves 500,000 verses for Devas, Pitris and Gandharvas. But if we add the totals of 30 hundred thousands + 15 hundred thousand + 14 hundred thousand, it does not come to 500,000. Should the total be 60 hundred thousand and not 6 hundred thousand? Then, it will be 30+15+14+1 becomes 60.