Offprint · The e Supplement · Supplement 2.7

Interest

Growth that never stops to count.

In 1683, Jacob Bernoulli asked a banker's question. Lend one coin for a year at one hundred percent. Paid once, it becomes two. Paid half at midyear and the rest at the end, with the half already earning, it becomes 2.25.

Pay more often and it grows more, but not without limit. Monthly gives about 2.613. Daily gives about 2.715. Paid every instant, it gives 2.71828…, and that number is e.

e is what growth comes to when it never stops to count.

e

Paid monthly: 2.61304. Paid every instant: e = 2.71828.

Figure One coin over one year at one hundred percent. The steps are the payments; the smooth curve is paying every instant.

“Interest.” The e Supplement, supplement 2.7 (24 September 2026). wap.mom/interest/