Ten Generations or Eleven?
10 generations from Adam to Noah
Adam, Seth, Enosh, …, Methuselah, Lamech, Noah
There are 10 generations if Adam and Noah are both included
10 generations from Noah to Abraham
Noah, Shem, Arpachshat, …, Nahor, Terah, Abraham
If we start with Noah, then there are 11 generations
If we start with Shem, then there are 10 generations.