# Number of possible hands in last two rounds of Texas hold-em

In the paper for the Poker AI, Libratus, the following is said:

The last two betting rounds, which are exponentially larger, are more coarsely abstracted. The 55 million different hand possibilities on the third round are grouped into 2.5 million buckets, and the 2.4 billion different possibilities on the fourth round are grouped into 1.25 million buckets.

I don't understand how the 55 million and the 2.4 billion hand possibilities in the third and fourth round are calculated. This seems like it would be obvious, but the calculations I'm doing give me different numbers, and I'm unsure what I'm doing wrong. I also know very little about Poker, so it's very possible I'm missing something.

Any help would be appreciated.

• One factor is whether "the number of hands" is the number of possible hands a single person can have, or whether it's the number of possible overall board states (that is, taking into account every player's hand). If the latter, we would have to know the number of players. – Acccumulation Aug 26 at 4:45