Hi kitty_cat, my boy loves numbers since young too! He can look at numbers all day if we allowed him to! Not sure if he is as good as your boy can recite 1-300 back and fro. But I have never thought of sending him for abacus at such a young age, wonder if any centre will admit such young age cos probably need parent to sit in and need to do homework… Does your boy know the true quantity when he counts from 1-300? Maybe you can start with that to teach him addition and subtraction yourself. I also expose my boy to skip counting, patterning, reading number in words through games as well. He can now recognise up numerals up to 4 digits. Oh, we also teach him how to say numbers in Japanese and dialects for fun lah, which he can pick up real fast since he has great interests in numbers.