錢經過銀行體系的運作，利用無窮等比級數及各個國家之央行所訂定的存款準備率， 銀行便可點石成金。將錢存放銀行，或向銀行借錢都會衍生利息議題，決定利息的多少除 利率外，採單利、複利計算、複利週期是每年、每月、每日或分分秒秒，都會影響利息的 多寡。如果將複利週期縮短到趨近於0 時，利息又與歐拉數e 巧妙連結。 僅使用數學工具中等比級數之技巧，便可把看似複雜的複利問題梳理清楚。當你能運 用簡單的數學揭開複利計算之面紗時，數學之美沉浸於生活之中。

The currency in circulation increases due to the Required Reserve Ratio announced by the Central Bank. Both savings and loans result in interest problems, which are decided by it is single interest or compound interest, the period of compound interest (e.g. yearly, monthly daily etc.) besides the interest rate. If the period of compound interest is limited to 0, the formula would be subtly related to Euler's number (e), namely e. By making good use of geometric progression, the seemly complicated compound interest problem would become much simpler.. And from then on, the beauty of the math shows.