Guides

Short, practical explanations of the maths behind everyday money decisions, each linked to the calculator that does the work for you.

How to Calculate Percentage Change (With Examples)
A plain-English guide to percentage increase and decrease: the formula, worked examples, percentage points, and the mistakes people make most often.
Discounts and Sales Tax: How to Work Out What You Really Pay
Learn how to calculate a sale price, stack discounts correctly, and add sales tax in the right order so the checkout total is never a surprise.
Monthly Budgeting for Beginners: A Simple Step-by-Step Method
Build a monthly budget in five steps: find your take-home pay, list fixed and variable costs, check what is left, and plan savings. Not financial advice.
How Loan Interest Works: Monthly Payments, APR and Total Cost
Understand how fixed-rate loan payments are calculated, why early payments are mostly interest, what APR means, and how the loan term changes total cost.