You play in a four deck game and get a 3 and a 9 for a Two card sum of 12while the dealer turns over an upcard of 4. Which option do you choose?
Stop with 12 vs 4
If the dealer has an upcard of 4, there is a Bust opportunity of 40%. Conversely, man will be a loser in 60% of the time. If you still take a third card in this situation with 12, win You slightly less and lose about 58% of your hands (pushes count for the difference).
This is a very close call. In fact, taking a card is almost as advantageous (if that's even the right word) as standing still.
There is very little advantage to standing here with 12 against a dealer's 4 - about half a percent, to be exact.
And you'll find, if you ever get into card counting, that if you have a rather low negative count (i.e., a higher than usual ratio of low value cards to high value cards that have yet to be played), you'll take one more card at 12 vs. a 4