Category
Calculators & Finance
Clear, worked-example guides to the calculations people actually need: percentages, loan repayments, interest, tax, discounts, tips and BMI. Every guide explains the formula in plain English and links to a free calculator that does the maths for you.
Calculators & Finance
How to Split a Bill and Calculate the Tip
No more awkward maths at the table. Here is how to calculate a tip, split a bill fairly, and handle tax — fast, in your head or with a tool.
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Calculators & Finance
How to Calculate ROI (Return on Investment)
ROI tells you whether an investment actually paid off. Here is the simple formula, a worked example, and the traps that make ROI misleading.
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Calculators & Finance
How to Calculate Your Exact Age in Years, Months and Days
Working out your precise age is trickier than it looks once months and leap years get involved. Here is how to do it correctly.
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Calculators & Finance
How to Calculate the Number of Days Between Two Dates
Counting the days between two dates by hand is error-prone. Here is how to do it right — for deadlines, leave, contracts and more.
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Calculators & Finance
Time Zones Explained: How to Convert Between Them
Scheduling across time zones causes endless confusion. Here is how time zones, UTC and daylight saving actually work.
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Calculators & Finance
How to Calculate the Average: Mean, Median and Mode
"Average" can mean three different things. Here is how to calculate the mean, median and mode — and when to use each.
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Calculators & Finance
How Currency Exchange Rates Work (and How to Convert)
Why is the rate you get never the rate you see online? Here is how exchange rates work and how to convert currencies correctly.
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Calculators & Finance
How Much Do YouTubers Actually Earn?
YouTube income is widely misunderstood. Here is how ad revenue really works — RPM, CPM and what views are actually worth.
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Calculators & Finance
How to Estimate Your Google AdSense Earnings
Wondering what your website could earn from ads? Here is how AdSense revenue works and how to estimate it from your traffic.
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