🧮 Numbers & Maths

15 browser-local tools · page 1 of 1

Numbers & Maths. The arithmetic people reach for a calculator to avoid: radix conversion that stays exact past the 2⁵³ limit of ordinary numbers, prime tests with their factorisation, fraction algebra that shows the working, a statistics run over a list you paste, combinations and permutations, Roman numerals both ways, a number written out in words, and duration maths in every unit at once.

15 tools on this shelf · 15 listed below

📐Unit ConverterLength, weight, volume, area, speed, temperature, time and digital storage — exact factors, every unit at once, nothing uploaded. 🔢Base ConverterAny whole number in base 2, 8, 10, 16 — or any base from 2 to 36 — computed exactly with BigInt, even numbers a desktop calculator overflows. 🧬Text ↔ BinaryText to UTF-8 bytes as 01101001 and back again, in binary, hex, octal or decimal — the honest way to see what a string really is. 🧷Prime Checker & FactoriserIs it prime? A deterministic Miller–Rabin answer for numbers up to 2⁶³, plus the full prime factorisation when it is not. 🍕Fraction CalculatorFractions that show their working: exact + − × ÷ with lowest terms by the Euclidean algorithm and the mixed-number form. 📈Statistics CalculatorThe full descriptive summary of any list of numbers — mean to quartiles — with the sample-vs-population choice made visible, not hidden. 🏛️Roman NumeralsNumbers to Roman and back with the real canonical rules — the page tells you IIII is a clock, not a document. 🔤Number to WordsAny number spelled out — including the cheque form banks actually ask for — exact up to 24 digits because it runs on integers, not floats. ⏲️Duration ConverterA raw span of seconds read the way people say it — 2d 8h 16m 40s — and back, refusing to pretend a month has a fixed length. 🧾Check Digit ValidatorDoes this card/IBAN/ISBN/barcode pass its own check digit? The published algorithm, the working printed, and the honest limit: validity is not ownership. 🎲Dice ProbabilityThe true 2d6 curve computed as exact counts — 21 of 36 outcomes are 7 or better — with the full distribution as a table. 🧮Combination CalculatorC(52,5) = 2,598,960 poker hands as an exact integer — combinations, permutations and factorials with no float ever touching the maths. ➗GCD & LCM Calculatorgcd(1071,462) = 21 with each Euclidean division printed as it happens — plus the LCM, the coprime verdict and the reduced fraction. 🔺Triangle SolverThree sides in, three angles, area and perimeter out — with the triangle inequality and the right/obtuse verdict stated honestly. 🔁Repeating DecimalSee the infinite inside a fraction: the long-division expansion with the repeating cycle marked, its length, and the remainder trail that proves it must repeat.

How these tools work

Each page names the method it uses rather than hiding it — BigInt long division for bases, trial division and Miller–Rabin for primes, the standard deviation formulas for the statistics — because a tool that will not show its maths is an ad farm with a text box. Everything runs on your device, so nothing you count is uploaded and the answer arrives even with the network switched off.

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