Two options on the board — “invest 1000 at 4% compounded annually?” — and one rule: your preference is worthless until mathematics backs it. Most good prompts hide a third answer behind the two printed ones: it depends — and the game is finding on what.
How we play
- Choose a side in silence. Commit before calculating feels safe.
- Defend with numbers, a table, or a sketch — not with vibes.
- Hunt the tipping point: where, exactly, does the better choice switch?
The interest duel, argued
- “Simple at 6%, obviously — six beats four.”
- “Table it. Year 10: simple interest has 1480. Simple is ahead, as promised.”
- “Year 25: simple has 1000(1.04)^{25} \approx 2666$. The curve caught the line.”
- “Graph both: the line and the curve cross just past year 20 — patient money should take the 4%.”
One variation
“Be paid $2000 today, or one dollar that doubles every day for two weeks?” Fourteen doublings settle it — and adding up every daily payment instead is a job for Series. Money prompts sharpen into Money Over Time, and the whole duel replays with real stakes in The Allowance Choice.
"It depends" is a mathematical answer
The strongest defence names the variable it depends on and the exact value where the choice flips. For the interest duel that variable is time — and every long-term decision in Your Financial Future turns on respecting it.