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Plain-English guides to the maths behind everyday calculations, with worked examples and a calculator for every method.
- Plain English Every formula explained
- Worked examples Real numbers, step by step
- Linked calculators Try each method instantly
- Checked figures Examples match our calculators
Latest articles
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Health guides
How to Figure Out Percentage of Body Weight Loss Formula
If you want to know how much of your starting body weight you have lost, calculating your weight loss as a percentage gives you…
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Health guides
How Many Calories Do You Need a Day?
Work out your daily calorie needs step by step: BMR with the Mifflin–St Jeor equation, your activity level, and a safe target for losing,…
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Finance guides
Understanding Compound Interest
How compound interest works, the formula with worked examples, why compounding frequency matters less than time, the Rule of 72, and how fees and…
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Math guides
How to Calculate Area and Volume
Area and volume formulas for every common shape, the unit conversions that trip people up, and a real concrete-slab example worked from start to…
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Health guides
Understanding BMI: Formula, Categories and Limits
How body mass index is calculated in metric and imperial units, what the adult categories mean, the lower thresholds for Asian populations, and where…
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Finance guides
Understanding Loan Payments: A Complete Guide
How a loan's monthly payment is calculated, what each part of it pays for, why longer terms cost more, and how overpaying cuts the…
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Math guides
How to Calculate Percentages: A Complete Guide
Three different questions all get called calculating a percentage. Here is how to tell them apart, and where the answers go quietly wrong.