You can start here for German numbers,
Luftwaffe Campaign Orders of Battle
Kampfgruppen - 1482
Stukagruppen - 365
Schlachtgruppe - 39
Jagdgruppen - 976
Zerstrergruppen - 244
total 3106 in Luft 2, 3 and 5. Subtract ~250 for Luft 5, so around 2850 bombers and fighters.
RAF Aug 13 1940
# Spitfire - 226
# Hurricane - 353
total 579
Since you agree that 1/3 of FC se fighters did not participate in the air battles over south east England, that gives 382 opposing the 2850 LW bombers and fighters. 5:1 was being generous as the ratio is 7:1.
On Sept 7 1940 there was
# Spitfire - 223
# Hurricane - 398
total - 621
which leaves 410 facing the bombers and fighters of Luft 2 and 3. I'll let you do the math for this date.