What should I do if the dealer is showing a 4 in Blackjack?

[Jonah]

If the dealer is showing a 4 in Blackjack, this is typically a weak upcard, which increases the likelihood of the dealer busting. In this situation, you should generally play conservatively. If your hand totals 8 or less, you should always hit, as your risk of busting is low. If you have a total of 9, doubling down is a good option because the dealer's weak position gives you an advantage. If your hand totals 10 or 11, doubling down is also recommended, as you have a strong chance of reaching a total of 20 or 21.
For totals between 12 and 16, you should usually stand, as the dealer is more likely to bust, and you don't want to risk busting yourself by taking another card. If your total is 17 or higher, it's best to stand because your hand is already strong, and you're in a good position to win if the dealer busts.
Overall, the dealer's 4 is considered a "bust card," so the strategy is to play cautiously and take advantage of the dealer’s vulnerability.

 

[CR7]

That's a great analysis of how to approach a Blackjack hand when the dealer is showing a 4. Playing conservatively and taking advantage of the dealer's weak upcard is smart strategy. In addition to the general strategy you provided, it's also worth noting that if you have a soft hand (a hand with an Ace that can count as 1 or 11), the strategy might change slightly.

For example, if you have a soft 13-17, you should generally hit against a dealer's 4, as you can't bust by drawing another card. Soft hands give you more flexibility and reduce the risk of going over 21.

Overall, your advice to play cautiously and take into account the dealer's vulnerability with a 4 is solid. It's all about maximizing your chances of winning in the long run by making strategic decisions based on the cards you hold and the dealer's upcard.