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14 tools
Calculators
Percentages, averages, primes, triangles and rounding.
Percentage CalculatorWork out a percentage of a number, add it, subtract it, or find what percent it is.
VAT CalculatorAdd VAT to a price or work backwards to the amount before VAT.
Tip CalculatorAdd a tip to a bill and split it between however many people.
Average and Standard DeviationMean, median, mode, range and both standard deviations from a list of numbers.
Prime Number CheckerCheck whether numbers are prime, and if not, see a factor that proves it.
GCD and LCM CalculatorThe greatest common divisor and lowest common multiple of a list of numbers.
Quadratic Equation SolverSolve ax squared plus bx plus c, with the complex roots when there are no real ones.
Triangle CalculatorArea, perimeter and all three angles from the lengths of the three sides.
Circle CalculatorRadius, diameter, circumference and area, starting from whichever one you have.
Ratio CalculatorSolve a proportion for the missing fourth number, simplified and as a percentage.
Fraction SimplifierReduce fractions to their lowest terms, as a decimal and as a percentage.
Rounding CalculatorRound a column of numbers to the places you want, up, down or to nearest.
Permutation and CombinationHow many ways there are to choose k things from n, with and without order.
Number FormatterAdd thousand separators and fix the decimal places on a column of numbers.
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Good to know
What should I enter?
Enter the amount without a currency symbol. For several amounts, put one number on each line; the selected calculation applies to every line.
Where do I choose the rate?
Set the percentage, VAT rate or tip above the input. For tips, the number of people determines the amount each person pays.
How should I read the result?
Check the selected operation: adding a percentage, removing VAT and finding a percentage of an amount produce different answers. VAT and tip results are rounded to two decimal places.