Ten, Five, Three, and Two Who Learn Torah Together
If ten, five, three, two or even one are studying Torah, the Shechina rests among them.
Ten represents a community
According to the Abravanel, Rebbi Chalafta comes to argue on the previous mishnayot - how to keep oneself from sinning. He argues on the Mishna that says that not only does one get reward for learning alone, Hashem's presence is there even if only one person is learning alone.
Delivered at the OU Israel Center, January 7th, 2019, Rosh Chodesh Shevat 5779