We had a four-year-old in preschool. He was sitting under the table writing down numbers for a long time. He had no time to talk to us. When he came out and we looked at what he had been doing, he said he wrote down all the multiplications. It turns out his brother in the fifth grade was learning the multiplication table and this little brother really wanted to do the same but did not have a multiplication table. He counted on his fingers to add each column and got the table right. A few days later, he knew multiplication. He would also comment on dates. If someone told them they had their birthday on June 12, he would say that is in 184 days almost immediately. On an excursion, we passed some status with birth and death dates and he would casually sum up he was 78 years old and 110 days old. She was born 33 years and 120 days before him. I think he was maybe more focused and willing to understand than necessarily so smart.