First math problem

Joshua was excited about finding a quarter today. I told him if he wanted to buy the sticker book he wanted so much, it would take 28 quarters!

"That's a lot, dad" he said.

I tried to explain to him that 4 quarters goes into a dollar, and that his book was $7.

"I don't really understand that dad"

"Ok, so if one dollar is 4 quarters, then to make two dollars, you have to add another 4 quarters. What is 4 + 4?"

Joshua quickly counted out on his fingers, and said, "8!"