Guides behind the numbers
Practical, number-first guides on the formulas people use every day — and the mistakes they make with them.
July 14, 2026 · 7 min read
Margin vs. Markup: The Pricing Mistake That Quietly Kills Profits
Margin and markup sound interchangeable. Confuse them and a target 25% margin quietly becomes 20%. See the math, the conversion table, and the discount trap.
July 14, 2026 · 8 min read
How Many Calories Should You Eat Per Day? What the Formula Actually Says
The 2,000-calorie label is not your number. See how the Mifflin-St Jeor formula computes yours, why plateaus are pure math, and how to set a safe deficit.
July 14, 2026 · 8 min read
How Much House Can You Afford? The 28/36 Rule, Explained with Real Numbers
The 28/36 rule worked through on an $85K salary, real amortization math on a $350K loan, and the hidden costs lenders never mention. Run your own numbers.