A childhood belief about counting

I can remember when I was little, I figured out how to count up to very large numbers for the first time. I was in the yard, and I counted outloud... I counted to fif-dee, then six-dee, then seven-dee, then eight-dee and finally nine-de,e and I kept going... nine-dee seven, nine-dee eight, nine-dee nine and finally --- TEN-dee! Ten-dee one, ten-dee two... until I got to ELEVEN-dee, then TWELVE-dee.

I was so proud, that after I got it down I did it in front of my mother, who then kindly corrected me, and explained that after nine-dee nine came one hundred.

I don't know how old I was, but the memory is as clear as a bell.