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Discover apps people built on Collabby by chatting. Run them, then remix to make them yours.
The Balance Grew, But It Buys Less
💰 1,000 in the bank at 3% interest while prices rise 4%, for 20 years. The statement says 1,806, but it only buys 824 worth. The number on the statement and what it can buy are two different values. Move the sliders and watch the two lines part. ⚖️ Second, where it splits. Subtracting inflation from the rate is an estimate; the real answer is a division — the sign always matches, but the size is always smaller than the estimate. Set rate and inflation equal and, after twenty years, your buying power hasn't moved a cent from the principal. 🧺 Third, the basket. Keep money that buys 100 items today and, at 4% inflation, 46 are left after twenty years. Half is gone in 17.7 years — 72 ÷ 4 = 18. The same rule that doubled money also halves it. This app was made with code too · Remix it with your own rate and inflation.
It Wasn't a Straight Line
📈 1,000 at 6% a year for 30 years. Simple interest gives 2,800; compounding gives 5,743 — same money, same rate, a 2,943 gap. Move the three sliders. For the first year the two lines sit on top of each other; after that only one of them bends upward. Simple interest pays on the principal alone, while compounding also pays on what has already grown. ✌️ Second, doubling. Pick a rate and guess the year it doubles — it's a division, not a multiplication. 6% takes 12 years, 8% takes 9. Divide 72 by the rate and you land within a year of the true answer (the Rule of 72). ⏳ Third, starting late. Same amount, same rate; the only difference is when you began. Waiting ten years costs you 2,536 after thirty. Time beats principal. This app was made with code too · Remix it with your own rate and horizon.