Organizing his numbers

I handed him the green cards with the pictures of the fingers and asked him to match the red cards with the numbers on them. He went a step further and put them in order. I was surprised. He decided to do the order all by himself. Then he counted to show he could use his fingers too. I need to move up to 2 hands now. I think he knows 6 & 7 but I have more hand cards and I need to find 6-10 number cards too.