on daf vov amid alef the gemara lists places where Hash-m tests himself. Hash-m is with 1,3,10 people. In perkei avos perkei 3 mishna 7 (wasserman artscroll siddur) it mentions 5 also. Why is 5 left off the list in berachos?
Possibly we may apply here a principle stated by Tosfos in Shevuos (19b, DH Shevuos), that the way of the Gemara is to shorten the Mishnah that it cites. So even though the Gemara in Berachos (6a) does not explicitly cite the Mishnah in Perek 3 of Avos, it is clear that the latter is a source for Berachos. However, the Gemara brings only the essential part of the Mishnah, so it is not necessary to list every number mentioned there. Since five is a number in the middle, one easily can infer that if the Shechinah is present with three and also present with ten, then it is also present with five. Therefore, it is not crucial to mention five.
G'mar Chasimah Tovah,