For Educators · Compound Interest
Compound Interest for a margin trade
Built for educators teaching it to a class. Drop a live demo into a lecture or assign it as a shareable link — no lab installs. Simulate a margin trade live below — adjust the inputs and watch it respond, right in your browser.
Compound Interest & InvestingLive
the eighth wonder
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Compounding means earning returns on your past returns, so growth accelerates over time. The gap between the balance line and your total contributions is pure compound interest — and it widens dramatically in the final years. Educational tool, not investment advice.
Data Inspector
Final balance$691,150
Total contributed$190,000
Interest earned$501,150
Governing equation
Reading this result: Rule of 72: at 7.0% a year, money roughly doubles every 10.3 years — about 2 doublings across your 30-year horizon. Each $500/mo contribution then earns returns on its own past returns, so the balance curve pulls away from your flat contribution line. Because compounding is exponential, most of the $501,150 in interest is created in the final years — time in the market matters far more than the amount. Educational tool, not investment advice.
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Frequently asked questions
- Is this good for educators?
- Yes — this version of "Compound Interest for a margin trade" is framed for educators teaching it to a class. Drop a live demo into a lecture or assign it as a shareable link — no lab installs.
- Do I need to install anything?
- No. It runs in any modern browser, free, with no account required.