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利息Interest

小树用一百枚教学币做时间实验。利息为什么可能越来越多，也可能成为借款负担？Mia uses 100 classroom coins in a time experiment. Why can interest grow, and also become a borrowing burden?

第 1 步：本金与利率分清Step 1: Separate principal and rate

先说清计算用的两个量。Name the two quantities used in the calculation.

Separate principal and rate
本金是最初借出或存入的金额。利率表示一定期间的利息比例。一百的本金，年利率百分之五。只看一年，利息就是五。Principal is the starting amount lent or deposited. An interest rate gives a proportion over a stated period. With principal 100 and annual interest of 5%, one year’s interest is 5.

第 2 步：复利把利息加入下一轮Step 2: Compounding adds interest to the next round

第二年还只按原本金算吗？Is the second year calculated only on the original amount?

Compounding adds interest to the next round
单利只按原本金计算。复利把前期利息计入下一期基数。按年复利，第二年从一百零五开始。计算频率必须与利率条件配套。Simple interest uses the original principal. Compound interest includes previous interest in the next base. With annual compounding, year two starts at 105. Frequency must match the rate terms.

第 3 步：计算结果不等于实际收益Step 3: A calculation is not a promised return

看到增长曲线，还要问什么？What should a growth curve make us ask?

A calculation is not a promised return
借款同样可能产生复利负担。费用、税和通胀会改变实际结果。浮动利率也可能变化。课堂固定利率不是现实收益承诺。Borrowing can also accumulate compounded costs. Fees, taxes, and inflation affect real outcomes. Variable rates may change. A fixed classroom rate is not a promise of actual returns.

🎮 机制实验室：观察，再判断🎮 Mechanism lab: observe, then decide

本金固定为一百。单利为一百乘以一加年数乘利率；复利逐年乘以一加利率。未计费用税与通胀。Principal 100. Simple balance = 100 × (1 + years × rate); compound balance = 100 × (1 + rate)^years. Costs, tax, and inflation omitted.

一句话记住它：Remember it: 利息要同时看本金、期间、计息规则与实际成本。Read interest together with principal, period, compounding rules, and real costs.
本金是最初借出或存入的金额。Principal is the starting amount lent or deposited.单利只按原本金计算。Simple interest uses the original principal.借款同样可能产生复利负担。Borrowing can also accumulate compounded costs.

来源与边界Sources and scope

Investor.gov · Compound Interest Calculator

利息算术：较高把握。教学币、固定利率均为假设，不推荐产品或借款决定。High confidence in the arithmetic. Coins and fixed rates are hypothetical; no product or borrowing decision is recommended.

核对日期：2026 年 10 月 6 日。文字与配图由 AI 生成；已做来源核对及程序测试，待人工复核。Checked 6 October 2026. Text and illustrations are AI-generated. Sources and software checks were performed; human review is pending.