The magic of compound interest

When my parents took me down to the bank to open my first account, I was also given my first lecture on the “magic of compound interest.” Back then the interest on my little account was probably 3.5%. I was told that if I kept that $10 in my savings account, I’d have $20 by the time I graduated from high school. “Where does the extra money come from?” I asked. No good answer came, other than “the magic of compound interest.”