Blog — How the Numbers Actually Work

This isn't generic financial advice. It's the math, the code, and the logic behind every calculator on Wanjaaro. From compound interest formulas to tax bracket data structures, I document exactly how each tool works — so you can see the numbers for yourself.

How to Avoid Tax on CD Interest (Legally) → How to Calculate CD Interest: Formula, Examples, and APY Explained → MRR Meaning: What Monthly Recurring Revenue Means and How to Calculate It → How Often Should Interest Compound? Daily vs. Monthly vs. Annual → How to Calculate Compound Interest by Hand (Step-by-Step) → Finance Calculations: Formulas, Methods & Tax Rules Explained → Free Finance Excel Templates for Budgeting & Investing → The Rule of 72 - A Simple Way to Estimate Doubling Time → Tax Amortization Benefit: What It Is and How It Works →

Every calculator on this site is built 100% client-side — your numbers never leave your browser. This blog exists to show you the exact formulas, data sources, and JavaScript logic behind each tool. No black boxes. Just transparent, verifiable numbers.

You'll find deep dives into the mathematical derivation of compound interest, how the Kelly Criterion is implemented, the IRS tax tables we hardcode each year, and the sorting logic behind debt snowball versus avalanche. If you're a developer or a numbers-minded user, you'll recognize familiar patterns. If you're just curious about how a calculation works, you'll get a clear breakdown.

This is where I document the engineering behind the site — not as a financial advisor, but as someone who's spent years building enterprise-grade fintech systems. If you're looking for personalized financial advice, this isn't the place. But if you want to understand exactly what the calculators are doing with your inputs, you've come to the right spot.

Got questions about a formula? Spot something that could be better? Drop me a line — I'm always refining these tools and love hearing from people who dig into the details.