No one technically.. I picked it up myself probably from TV. I knew basic math at 4, I don't know how though...all I remember is starting school (I never attended nursery, just went into public school at 4) and when they started the math topic on the 3rd day, I just kept answering all the math questions correctly but doing so, I singled myself out and so no one wanted to play with the smart kid... 4/5 year olds were mean, also didn't help that most of them went to nursery and preschool together so they knew each other...
My mother wasn't really encouraging academically when I was little, (or in general) most things I learnt growing up were self taught or because of school.