what you are talking about is Jama3a "grouping in prayer,
but for Jum3a it is according to what system you are using "Mathhab"
for Shafii and Hanbali , it should be 40 men
for Malki it should be 12
for Hanafi it can be done by 3 only but one of the three should be able to make imamah. http://www.islamweb.net/ver2/Fatwa/ShowFatwa.php?lang=A&Id=7637&Option=F...
if you can read arabic
what you are talking about is Jama3a "grouping in prayer,
but for Jum3a it is according to what system you are using "Mathhab"
for Shafii and Hanbali , it should be 40 men
for Malki it should be 12
for Hanafi it can be done by 3 only but one of the three should be able to make imamah.
http://www.islamweb.net/ver2/Fatwa/ShowFatwa.php?lang=A&Id=7637&Option=F...
if you can read arabic