Learn Percentages
In-depth guides on percentage calculations, formulas, and how to apply them in finance, shopping, health, taxes, and everyday decisions.
How to Calculate Percentage Increase and Decrease
Learn the formulas and step-by-step methods for calculating percentage increase and decrease, with real-world examples from finance, business, and everyday life.
Updated 2026-03-30Markup vs. Margin: What's the Difference?
Understand the critical difference between markup and margin percentages. Learn the formulas, see real examples, and avoid the costly mistake of confusing the two.
Updated 2026-03-30Percentage Tips for Shopping: Discounts, Sales Tax, and Savings
Master the percentage math behind shopping — calculate discounts, stack coupons, figure out sales tax, and compare unit prices like a pro.
Updated 2026-03-30Understanding Interest Rates and Compound Interest
Learn how interest rates work, the difference between simple and compound interest, and how to calculate how your money grows over time.
Updated 2026-03-30Percentages in Health and Nutrition: BMI, Body Fat, and Daily Values
Understand how percentages are used in health metrics — from BMI and body fat percentage to daily nutritional values, calorie tracking, and macronutrient ratios.
Updated 2026-03-30How to Calculate Tax Percentages: Sales Tax, Income Tax, and Effective Rates
Learn how to calculate sales tax, understand income tax brackets, find your effective tax rate, and handle tax-inclusive and tax-exclusive pricing.
Updated 2026-03-30Percentage Formulas Cheat Sheet: Every Formula You Need
A comprehensive reference of all percentage formulas — from basic calculations to percentage change, reverse percentages, compound growth, and more.
Updated 2026-03-30How to Calculate Percentages in Excel and Google Sheets
Learn the exact formulas to calculate percentages in spreadsheets — percent of a number, percentage change, running totals, and common mistakes to avoid in Excel and Google Sheets.
Updated 2026-04-01Percentage vs. Percentile: What's the Difference?
Percentage and percentile sound similar but mean completely different things. Learn the key distinction with examples from test scores, salary data, growth charts, and statistics.
Updated 2026-04-02The History of the Percent Sign: From Ancient Rome to the % Symbol
How did the % symbol come to be? Trace the history of percentages from Roman tax calculations through medieval Italian merchants to the modern percent sign we use today.
Updated 2026-04-03