Why 20% Off and Then 10% Off Does Not Equal 30% Off
Take 20% off, then another 10% off, and you save 28%, not 30%. Learn why stacked discounts combine this way and when the order of coupons matters.
Articles, page 10
Plain-English guides to the numbers in everyday life: how a calculation works, where people go wrong, and which tool to reach for.
Start Saving Early or Save More Later? What the Math Says
Ten early years of saving can match or beat thirty later ones, depending on the return. A side-by-side example shows exactly where the crossover happens.
US vs Imperial Gallons, Pints, Cups and Spoons
The US and imperial systems share unit names but not sizes. This guide compares gallons, pints, fluid ounces, cups and spoons so a recipe or label is never off by 20%.
Waist Measurements: Waist-to-Height and Waist-to-Hip Ratios
A tape measure can say more about abdominal fat than the bathroom scale. Learn where to measure, the common cut-offs, and how to calculate both ratios by hand.
Waste Allowance: How Much Extra Material Should You Buy?
Every building job loses some material to cuts, breakage and uneven ground. A waste allowance is the extra you add so the project does not stop halfway.
The 10% Rule for Weekly Mileage and Recovery Weeks
Raising mileage by 10 percent a week sounds modest until you see it compound. Here is the maths, the limits of the rule, and a simple cut-back week pattern.
What BMI Can and Cannot Tell You About Your Health
Two people can share the same BMI and have very different bodies. Here is what the number was designed for, where it falls short, and what to pair it with.
What Makes a Password Strong: Length, Randomness and Entropy
A strong password is one that is hard to guess among all the possibilities. Here is how to count those possibilities, compare passwords in bits, and avoid common traps.
What Is Included in a Mortgage Payment? PITI Explained
The loan repayment is only part of what you pay each month. Learn what PITI stands for, how escrow works, and how a down payment changes the monthly figure.
Why a 1 TB Drive Shows 931 GB: Decimal vs Binary Units
No space is missing from a 1 TB drive that reports 931 GB. Two definitions of the same prefixes are in use, and the gap grows with each step up in size.
Why a 30% Markup Is Not a 30% Margin (and How to Convert)
Adding 30% to your cost does not leave you with a 30% margin. Learn why the two figures differ and how to convert between them without mistakes.
Why a Cup of Flour Weighs Less Than a Cup of Sugar
Cups and grams are not interchangeable because ingredients differ in density. Here is how to convert between them, and why weighing beats scooping for baking.