math problem

2 - 4 - 8 - 16 - 32 - 64.
126

It's 2 to the sixth power or 64. You can also do this by hand.

At the end of six rounds, there is one team
At the end of five rounds there are two teams
At the end of four rounds there are four teams
At the end of three rounds there are eight teams
At the end of two rounds there are sixteen teams
At the end of one round there are thirty two teams
Before the first round there were sixty four teams.

That's incorrect.

No it's not.