Guides, tips & how-tos

How ratios work — what they express, how to simplify them, and how to use them for splitting amounts, scaling recipes and mixing proportions.

How to calculate ROI on any investment — the simple formula, what counts as a "good" ROI, and common mistakes in calculating it.

How changing a loan's tenure affects your monthly payment and the total interest you pay — and how to decide which tenure makes se...

What a JWT token is, how the three parts work together, and what to check when debugging authentication issues with tokens.

How compound interest actually grows savings over time — the effect of starting early, adding regularly, and why small differences...

Google Analytics 4 basics for small websites — what it tracks, the reports that actually matter, and how to read them without gett...

The break-even point tells you exactly how many units you need to sell (or what revenue you need) before your business starts maki...

Calculate GST or VAT on a price — adding tax to a base price, removing tax from a tax-inclusive price, and presenting tax correctl...

How to calculate percentages quickly — the three types of percentage problems most people encounter, with plain formulas and pract...

Calculate percentage increase or decrease between two numbers — the exact formula, when to use which version, and how to reverse i...