There are many versions of blackjacks and in most of the versions of blackjack, there are times when you have to split the pair. You play each hand and you do not get two chances while playing a normal hand. If you are playing for a high level, it is important that you know when to split. As they are only 10 card values, it is up to you to memorize every situation.
Always split aces
There are some cases in blackjacks when you know you can spit as showing this will give you much higher chances to show a stronger hand. When you play two aces as on hand, you will always start on the 12 value and having a 9 can give you 21 to bring back the 12. If you split it four ways to get a 12 you need to have a 10, Joker, queen or king.
Always split eights
Every blackjack will tell you to split an eight other than aces as it is difficult to play a hand when you have an eight in hand. The chances you get are mathematically not good. When you are playing an eight, you start out with a 16 which is weak and if you hit not, you risk proposition. This will give you a 60% chances of loosing, which is not good. Also, if you try to split you might get a bust on the first hit but you have chances of getting a favourable hand.
Always re-split aces or eights, if you are dealt a second pair
When the dealer gives you two cards on each for a new hand, you get a second pair. You can treat it as its own and split it again. This move requires you to triple you bet and house rules might vary here as most blackjack games allow you to split the maximum of three times, if you play four hands.
You should never split tens
This is a common mistake as if you are sacrificing the 10 you are essentially losing a great hand. If you are playing 10 you are essentially losing a value of 20 which is quite good and to split 10s you need aces to improve the stance which will give ti an equal or lesser value. Expert suggests that it makes sense to split a 10 when the dealer shows 5 or 6 as this way you can have a chance at getting a 20.
Never split fours
If you split four, you are essentially giving two weak hands which make no sense as splitting requires you to double your original wager which means you will be splitting and losing money propositionally.