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Deep-dive guides on AI agents, agent orchestration, MCP, and developer tooling.

5 posts found

Fintech

ROI vs. IRR vs. Payback Period: Why the "Best" Investment Depends on Which One You Ask

Three investments, three different "winners" depending on which metric you compute — here is the arithmetic behind ROI, IRR, and payback period, and exactly when each one lies to you.

August 7, 2026 · 6 min read

Fintech

The IBAN Checksum Explained: How Mod-97 Catches a Mistyped Bank Account Before It Costs You

IBANs aren't just a longer account number — the last two digits are a mod-97 checksum that catches typos and transposed digits before a wire transfer goes to the wrong bank. Here's the actual arithmetic, worked through on a real-looking IBAN.

August 6, 2026 · 5 min read

Fintech

Margin vs. Markup: The Pricing Mistake That Quietly Eats Small-Business Profit

A 25% markup and a 25% margin are not the same number, and mixing them up systematically underprices every product you sell. Here's the actual math, a worked example, and why the confusion never seems to die.

July 31, 2026 · 5 min read

Fintech

How Amortization Actually Works: Why Two Loans at the Same Rate Cost Different Amounts

Two borrowers with identical 6% mortgages can pay $156k or $348k in interest. The rate isn't the culprit — the term and the amortization schedule are. Here's the math, with real numbers.

July 19, 2026 · 6 min read

Fintech

The Luhn Algorithm Explained: How Credit Card Numbers Catch Their Own Typos

The Luhn checksum baked into every credit card number catches keystroke errors, not fraud — here is the math behind it, why card network prefixes matter, and where naive validators break.

July 8, 2026 · 6 min read