One of the ways that I thought might be fun is with polyhedral dice. The games you can play are endless - and we've played a few!
We have 20 side, 12 side, 10 side, 8 side and 4 side dice.
The first game that George 2 and I played was a simple multiplication of two numbers thrown on two dice.
Then we played some family games of adding numbers together. Each time you throw the die, you add the number to your previous throw and the first to get to 50 wins. They quickly worked out that the 20 sided die would likely get you there faster! It was great fun, and the older children helped the younger children with the addition. It got pretty fast and competitive after a while.