Simple and compound rule of three: practical everyday examples
Learn how to identify direct and inverse proportions without memorizing rigid formulas, know when to cross-multiply, and solve real-world problems in shopping, recipes, and work.
How to calculate real fuel economy using the full-tank method
Step-by-step practical guide to discover your vehicle's actual km/L or MPG in everyday driving, avoid common measurement traps, and convert it into real cost per km.
How much does owning a car really cost per month?
Add up fuel, insurance, taxes, maintenance, and parking, turn yearly expenses into monthly installments, and see how depreciation impacts the true cost of ownership.
How to calculate discounts and percentages in your head
Learn mental math benchmarks using 10%, 1%, and simple fractions to calculate discounts instantly on the go and verify store deals.
Shrinkflation: how to spot when product packages get smaller
Learn how to calculate true price changes per kilo or liter when packages shrink, and discover what labeling regulations require brands to disclose.
Price per kg and per liter: how to compare packages without calculation errors
Learn the exact formula to compare products with different package sizes, spot shrinkflation tricks, and always pick the most economical option on the shelf.
How to truly save at the supermarket by comparing unit price
Avoid deceptive "family-size" packages and see how calculating unit price per kilo, gram, or liter can reduce your grocery bill by up to 25%.
Ethanol or gasoline: when the 70% rule fails and how to do the real math
The popular 70% rule is just an average. Understand why it might recommend the wrong fuel for your car model and how to calculate with real fuel efficiency.
How much does it cost to drive 1 km in your car (and why it is not just gasoline)
Factor in vehicle taxes, insurance, maintenance, tires, and depreciation to discover the real cost per kilometer driven, illustrated with a full example.
Physics formulas for college exams: high-frequency topics with solved questions
Major entrance exams do not provide formula cheat sheets. Explore the formulas that appear most frequently, what every variable means, and solved examples.