Guides
Clear, practical explanations of the maths behind everyday money decisions — how to add and remove VAT, work out a percentage, price a product, and more. Each guide shows the method and links to the calculator that does it for you.
- Study
How to Calculate Your Grade: Test Scores, Weighted Grades, and Finals
Turn any test score into a percentage and letter grade, combine weighted coursework and exams, and work out exactly what you need on the final — with worked examples and a grade-band table.
- Shopping
How to Calculate a Discount (Percent Off, Reversed, and Stacked)
Work out any sale price in one step, reverse a discount to find the original, and see why 30% off then 20% off is not 50% off — with worked examples and a quick-reference table.
- Money
Salary to Hourly: How to Work Out Your Real Hourly Rate
Convert an annual salary to an hourly rate, then adjust for unpaid overtime, holiday, and commuting to find what you actually earn per hour — with worked examples.
- Maths
Percentage Increase and Decrease, Explained with Examples
How to calculate a percentage increase or decrease, why successive changes don't add up, and how to reverse one to find the original — with shopping, salary, and stat examples.
- Money
How to Calculate a Pay Raise (and What Counts as a Good One)
Work out the percentage of any pay rise, convert it to real take-home money, and judge it against inflation — with worked examples for hourly, monthly, and annual pay.
- Business
Markup vs. Margin: The Difference Every Business Owner Should Know
Markup and margin use the same two numbers but divide by different things — and confusing them quietly erodes profit. Here's the distinction, the formulas, a conversion table, and worked examples.
- Maths
How to Calculate Percentages: The Complete Guide
The three percentage problems that cover almost everything — finding a percent of a number, working out one number as a percent of another, and percentage change — explained with plain-English methods and worked examples.
- Tax
How to Work Out VAT: A Plain-English UK Guide
Add VAT, remove VAT, and avoid the most common mistake — with the exact formulas, the UK 20%/5%/0% rates, and worked examples for every step.