My son learned money math at three using computer games. We got him a Reader Rabbit First Grade when he was three for the "reading" part of it because he seemed to be reading and comprehending stuff at first grade level. But it had math activities also and I think that is where he learned about coins. His interest in counting money led to counting by fives and tens and 25s. Knowing how to count by fives led to learning to read an analog clock to the minute which he could do in Kindergarten. I think he somehow related it to counting nickles and pennies. I remember when he was five, the older kids in his acting class were surprised that he could count out his own money for the vending machine.
My son also liked doing mental math and I heard him tell the Kindergarten teacher when she was testing him to see if he was ready for Kindergarten that you can use blocks to figure out answers to math questions but he preferred looking at the first number and counting up. He could also do a little bit of multiplication at that time and he could also read very well, but she didn't think he was ready for Kindergarten because he couldn't draw very well or color in the lines. It didn't matter that he has hypotonia and a physical reason for his difficulties.
I sometimes wonder if maybe other kids are just not given a chance to learn what my son learned at home playing games because some teachers in our public schools care more about getting their students to color in the lines.
