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Percentage calculatorFour percentage calculations in one: X% of Y, what percent X is of Y, and increasing or decreasing a value by a percentage.Average (mean) calculatorCompute the mean, sum and count of a list of numbers.Derivative CalculatorCompute single, partial, implicit and directional derivatives symbolically.Percentile calculatorFind the value at a given percentile in a list of numbers.CalculatorEvaluate math expressions with parentheses, powers and modulo, live.3D Distance CalculatorCompute the distance between two points in space, with an isometric view, the Δx / Δy / Δz components and the midpoint.Absolute Value Equation SolverSolve absolute-value equations like |x+3| = 5, 3|x+2| = 12 or |x+1| = |x−3| with step-by-step case analysis and exact solutions.Absolute Value Inequality SolverSolve absolute-value inequalities such as |x+3| < 5 or |x−2| > 3 and get the solution as an interval, with AND/OR reasoning explained step by step.
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BMI calculatorCompute your Body Mass Index and weight category.VAT calculatorAdd or remove VAT from a price at any rate.Temperature converterConvert between °C, °F, K and more. Free temperature converter, instant and accurate.QR Code GeneratorCreate a QR code from any text or URL — free.Password generatorGenerate a strong, random password — free and secure.Word counterCount words, characters, sentences and reading time instantly.Hash generatorCompute 15 hashes (MD5, SHA-256, SHA-3, CRC-32…) of a text or a file.UUID generatorGenerate UUID v7, v4, v5, v3, v1 or v6 in bulk, in several output formats.Base64 Encoder / DecoderEncode and decode Base64 online — free.JSON formatter, minifier and validatorFormat, beautify or minify JSON — with instant validation.Color converterConvert a colour to HEX, RGB, HSL, HSV, CMYK, LAB and OKLCH, with contrast.Regex testerTest a regular expression and see what it does: matches highlighted in the text, every capture group listed, a replace panel, and the pattern read back to you piece by piece. Flags are toggles that say what they change, and a pattern that could freeze the page is flagged before you run it.
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ExplainerThe Mixing Ratio on a Dye Box Sets the Peroxide, Not the Texture120 ml at 1:1 is 60 and 60; at 1:2 it is 40 and 80. The developer's share goes from half the mix to two thirds, and so does the peroxide that does the work.ExplainerAn Absorbance of Two Means One Per Cent of the Light Gets Through6,220 M⁻¹cm⁻¹ at 100 µM through 1 cm gives A = 0.622, and 23.9 % of the light emerges. Double the path length and A doubles to 1.244 — the scale is logarithmic, and that is where it breaks.ExplainerSalting Pasta Water Raises the Boiling Point by Two Tenths of a DegreeFifty grams of salt in five litres is 0.171 mol/kg and buys +0.175 °C. Reaching a full degree would take 285 grams — most of a box.ExplainerOsmotic Pressure Counts Particles, Not Molecules0.15 M of a salt that splits in two and 0.30 M of one that does not give the identical 7.64 atmospheres. Only the particle count reaches the membrane.ExplainerA Buffer Holds Its pH by a Ratio, So Dilution Changes NothingEqual amounts of a weak acid and its base give pH = pKa exactly, at any concentration. Blood runs the same equation at a 20:1 ratio and lands on 7.40.ExplainerThe Same Burette Reading Gives Two Different Concentrations24.80 mL of 0.1 M titrant into 25.00 mL of analyte gives 0.0992 M — or 0.0496 M if the analyte releases two protons. The stoichiometry is typed, not measured.