Do you know the game Addition Top-It? I have a few different versions but recently discovered another one!
With younger children I play in partners. Each child turns over a card (so there are two showing at once), then have a race to add the cards together and say the answer. The first to say the answer wins the card (if it's a draw, each player gets a card).
As children progress with their understanding of addition and subtraction you can play in groups of three. One person is the dealer and two are the players. The dealer gives each player a card. Players don't look at their card and put it on their forehead so the other player can see their card. Then the dealer adds the two cards together and tells the players the answer. The fastest player to work out what card they have on their head wins. (So many great number strategies are used in this game - best thing is all children playing have to do some Maths!).
Recently, I tried playing this game as purely subtraction practise. Children were in their groups of three and instead the dealer would say "When I subtract this card (pointing to one) from this card (pointing to the other) I get an answer of..." and the players had to guess what card they had. It worked great! Children definitely had to think and remember to always subtract from the big number!! I was so glad I altered this game - it worked so well! I was so proud of the kiddos!