Reference library
Playbooks and Reference Helpers
Use Playbooks when you want the formula, definition or printable helper behind a calculator. For longer story-led reading, use Articles.
Use articles, packs or worksheets instead
These pages are better when you want a longer guide, a printable sheet, a grouped calculator path or a short activity.
Articles
Longer guides that explain decisions, tradeoffs and real-world calculator use.
Printable packs
Worksheets for budgets, study plans, travel, party food, energy and work pricing.
Calculator packs
Grouped calculator paths for common planning jobs and comparisons.
Challenges
Short activities that turn calculator results into repeatable experiments.
Formula playbooks
Date Math Playbook
Countdowns, birthdays, weekdays and leap years.
Time Planning Playbook
Minutes, breaks, movie marathons and sleep-cycle estimates.
Conversion Formula Playbook
Metric, imperial, cooking, geometry and comparison math.
Cooking Math Playbook
Cups, spoons, milliliters, servings and temperature.
Travel and Fitness Playbook
Distance, pace, speed and fuel planning.
Percentage Playbook
Discounts, VAT, tips, splits and rounding.
Value Comparison Playbook
Pizza, subscriptions, unit prices and recurring costs.
Small Money Playbook
Daily habits, subscriptions, streaks and savings goals.
Investment Returns Playbook
ROI, CAGR, dividends, fees and shortcuts.
Crypto Calculation Playbook
Profit, market cap, staking and risk sizing.
Home Bills Playbook
Mortgage, rent, electricity, paint and moving estimates.
Work Money Playbook
Paychecks, overtime, invoices, meetings and freelance rates.
Health Estimate Playbook
BMI, calories, protein, hydration and activity estimates.
Student Calculation Playbook
Grades, finals, GPA, study pacing and reading time.
Creator Toolkit Playbook
Text length, timestamps, images, colors, URLs and JSON.
Plain-English explainers
Glossaries
Mortgage Basics Glossary
Payment, deposit, loan term and interest definitions.
Energy Cost Glossary
Watts, kilowatts, kWh and running-cost terms.
Grade and GPA Glossary
Credits, grade points, weights and course averages.
Web Format Glossary
JSON, URL encoding, aspect ratios and contrast terms.
Hourly Rate Glossary
Work pay, freelance rate and hourly conversion terms.
Invoice Basics Glossary
Subtotal, discounts, tax and invoice total terms.
Printable helpers
View all printable packsMonthly Budget Worksheet
Printable boxes for income, bills, flexible spending and savings.
Study Planner Worksheet
Printable topic, reading, practice and buffer-day planner.
Home Energy Audit Checklist
Printable device shortlist, wattage and action checklist.
Party Food Planner Worksheet
Printable guest, snack, pizza, drink and shopping planner.