hello to everyone

i was thinking my entrance to casino is always to go directly to bj tables cut the game by putting down some money on the table and sitting down to play first shoe i catch flat betting and bs like a gambler that cant wait for the action

but ..... what if i sit at a table that from 6 decks is already played 3 decks and by sitting down in the first one or two hands i see a +6 (games is with surrender -0.28 he) and i consider that i play at tc 1 and betting like that.i just put mentaly all the decks that allready was played and didnt count them behind cut card .

what u say ??is mathematical correct ?