What is it about seven who ate bread joining with others to make a minyan for zimun that isn't possible with six who ate bread? My thought was that six can split into two zimunim, but seven is a 'Ruba de'Mink'ra' in that way, being more than six. Please let me know, including a source. This question was referred to me in my community.
Jonathan Goldfarb, Indianapolis, USA
I didn't find any poskim who refer to the fact that six can split into two zimunim since the mishna itself stresses that not just six can split but even seven, eight and nine can split. Thus it would not seem to be the criterion for whether to include them.
The real criterion here is that seven is more than two thirds and six is less than two thirds and we see throughout the sugya that two out of three are significant in many ways, for example the fact that one has to stop his meal and answer the other two and they don't need to stop for him.
Rabbi Y.D. Soloveitchik in his Shiurim suggests that for Zimun we require a "Kvius D'Chaburah" and therefore you need a larger majority because a Chaburah (a "get-together" group) is different than a Minyan which can be patched together from six who didn't Daven.
Yoel Domb