Why do blackjack strategy charts say when the dealer has a 4 up to hit an A,2 / A,3 but to double down on A,4 / A,5? Because A,2 thru A,5 all have 5 cards that would make the hand 17 or higher
A,2,3,4,5,6,7,8,9 and 10s*4 = 13 card possibilities that could be dealt to you when taking a card...