Money & investing · course 70 of 105
Personal Finance by the Numbers
Do the maths behind everyday money decisions, from compound interest, APR and savings to loan and mortgage payments, paying off debt and inflation. Maths, never advice.
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Preview
What it teaches
The money maths behind everyday decisions: simple vs compound interest, compounding frequency and APY (how to compare two savings rates), APR vs interest rate, saving a fixed amount every month, loan payments and where each payment goes, what a 15- vs 30-year mortgage really costs, why a card payment that only covers interest never ends, debt snowball vs avalanche, an emergency-fund target, and what inflation does to cash. The AI asks 3 questions, places you, shows a short card per module, then gives you one problem at a time and checks your answer against keys computed by script.
No advice, ever. It never tells you what to buy, borrow or invest in; it teaches the maths so you can compare offers yourself.
How long
30 items. About 15-50 rounds plus a 12-item final (about 15 if you already know the basics, about 50 for a beginner who misses a lot): 2 sessions (estimate, not timed with a real student). The tutor gives a one-line save code at the end of each session.
The modules
4 modules, drilled one item at a time.
- M0
The words
Concept questions
- M1
Interest that grows
Maths
- M2
Loans and credit cards
Maths
- M3
Paying off debt and budgeting
Maths
Before it teaches, it asks
- 1What brings you here: a loan or card you’re paying, saving up, a class, or curiosity? Which of these words do you already use: APR, APY, compound interest?AI voice (ElevenLabs)
- 2$1,000 at 5% compounded yearly for 3 years. Total?
- 3A $20,000 loan at 6% APR for 60 months has a monthly payment of $386.66. In the first payment, how much is interest and how much is principal?
What’s exact, and what isn’t
Show
Straight from the course’s own notes.
- Computed by script
- Every key, with exact decimals; formula answers cross-checked by simulating them month by month; the card and payoff simulations were also confirmed at build time by a second, separately written cents-based simulation.
- Sourced
- APR from the CFPB; compounding, APY, the loan formula, snowball/avalanche and real rates from Wikipedia; short quotes matched word for word on 2026-10-10.
- Simplified on purpose
- Fixed rates, no fees in the loan maths, card interest charged monthly at APR ÷ 12.
- Not in it yet
- Taxes, retirement accounts, credit scores, variable rates.