When I was a kid, (around 4 years old), I was playing super nintendo games, because my dad was playing these too. You easily find out that mario has 3 lives, and that once it gets to zero, it's game over. You find coins, and once you have 100 coins, you win one more life.
You aren't searching for maths, it comes to you directly. Then some games (like zelda), needs you to learn slightly more complex maths, because you find rupees (coins, basically), and you can use those to buy things. Do I have enough money to buy the stuffs I want ?
It also requires you to know what are the characters saying, as it's all text, you need to call your dad for him to read for you, but it encourages you to start learning how to read by yourself, and instead of just going to school and learn how to read there, you are the one asking poeple to teach you how to do so.
It was fun, because the game wasn't about learning how to read, or learning how to count to win, you had to rescue the princess, and learning how to read was just one of the requirements on how to do so.
The side effect was to turn me into a geek, but entering school, I knew how to count and read.