Guides & how-tos
Practical, no-fluff explainers on money, math and everyday calculations — each one paired with a free tool so you can try the numbers yourself.
How to Calculate VAT Backwards (Remove VAT From a Gross Price)
Stacked Discounts: Why 20% + 10% Is Not 30%
How Old Is My Dog in Human Years? The Science (Times-7 Is Wrong)
How to Split Rent With Roommates Fairly (4 Methods Compared)
Running Pace Explained: What's a Good Pace, and How to Predict Your Race Time
What Is a Good GPA? Honest Benchmarks for College and Grad School
How Much Do I Need to Retire? The 4% Rule, Real Numbers and Why 10× Your Salary Is a Rough Guess
How Much House Can I Afford? The 28/36 Rule, Real Numbers and What Lenders Actually Check
How Strong Is Your Password? The Math Behind Password Strength
How to Calculate a Loan Payment by Hand (and Check It With a Tool)
Percentage Change vs. Percentage Difference: What's the Actual Difference?
