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Practical guides that pair with our calculators — how the numbers work, and how to use them.
Latest articles
How to Find a Square Root (and What It Really Means)
What a square root is, how to estimate one by hand, and the difference between square roots and cube roots — with worked examples and a calculator.
28 September 2026 · 3 min read❤️ HealthWhat Is My Ideal Weight? The Formulas Explained
There's no single ideal weight. Here's what the Robinson, Miller, Devine and Hamwi formulas say, how they compare to a healthy BMI range, and how to read the numbers sensibly.
28 September 2026 · 2 min read🔁 ConversionConverting mph to km/h (and Back Again)
The simple factor for turning miles per hour into kilometres per hour, quick mental shortcuts, and how mph, km/h, m/s and knots relate.
28 September 2026 · 2 min read📅 Date & TimeHow to Calculate the Hours Between Two Times
Work out the hours and minutes between a start and end time — including overnight shifts and unpaid breaks — by hand or with a calculator.
28 September 2026 · 2 min read➗ MathHow to Calculate Percentage Change (Increase and Decrease)
Work out the percentage increase or decrease between two numbers, why the original value is the anchor, and how percentage change differs from percentage points.
21 September 2026 · 2 min read❤️ HealthBody Fat Percentage: What It Means and How to Estimate It
What body fat percentage measures, why it can tell you more than BMI, and how the US Navy tape method estimates it from a few simple measurements.
21 September 2026 · 2 min readBrowse by topic
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