身边的经济学·社会常识英语30篇（2）

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复利与72法则粗算

Put $1,000 in an account earning 6% yearly interest, and reinvest all gains—you’ll double it in about 12 years.
The Rule of 72 gives a quick estimate: divide 72 by your annual return to get doubling time.
At 4%, your money doubles in 18 years; at 9%, just 8 years—small changes create big gaps over decades.
Starting at age 25 versus 35 means nearly *double* the final amount—even with identical contributions.
Compounding works best when time, consistency, and patience all line up—not just high returns.
Credit card debt compounds too: a 19% APR doubles what you owe in under 4 years if unpaid.
Banks highlight 'APY' (annual percentage yield) to show compounding effect—but many skip reading fine print.
Visualizing growth as a snowball rolling downhill helps explain why early action matters most.
You don’t need complex math—just remembering '72 ÷ rate = years' builds useful financial instinct.
Time isn’t neutral; it’s your quietest, strongest ally—or your loudest cost.