Convert, analyze, and visualize numbers. All computed right in your browser.
Unit Converter
Convert between length, weight, temperature, and speed.
How it works: Pick a category, enter a value, choose source and target units. Built-in conversion factors for length (mm to mile), weight (mg to lb), temperature (C/F/K), and speed. Example:10 km → 6.214 miles. 100°F → 37.78°C.
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Number to Words
Spell out any number, up to trillions.
How it works: Breaks the number into groups of three digits (ones, thousands, millions, etc.) and converts each group to its word form. Handles up to quadrillions. Example:128500 → "One Hundred Twenty-Eight Thousand Five Hundred". 42 → "Forty-Two".
In words
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Words to Number
Type a number in words, get digits back.
How it works: Parses English number words like "one hundred twenty-five" back to digits. Supports "and", hyphens, and scale words (hundred, thousand, million). Example: "one hundred twenty five" → 125. "Three million five hundred thousand" → 3,500,000.
Numeral
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Roman Numeral Converter
Convert between numbers and Roman numerals (1–3999).
How it works:Number → Roman: repeatedly subtracts the largest possible Roman symbols. Roman → Number: parses each character with subtractive rule (e.g., IV=4, IX=9, XL=40). Example:1994 → MCMXCIV. MCMXCIV → 1994.
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Binary / Hex / Decimal Converter
Convert between binary, octal, decimal, and hex.
How it works: Parses the input value in its source base, then converts to the target base. Supports binary (2), octal (8), decimal (10), and hexadecimal (16). Example:255 decimal → FF hex → 11111111 binary.
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Fraction ↔ Decimal
Convert fraction to decimal, or decimal to fraction.
How it works:Fraction → Decimal: simply divides numerator by denominator. Decimal → Fraction: uses the decimal places to form a fraction, then simplifies by GCD. Example:3/4 → 0.75. 0.625 → 5/8.
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Ratio Calculator
Simplify a ratio or scale it to an equivalent one.
How it works:Simplify: divides both numbers by their GCD. Find Equivalent: given a new value for A, calculates proportional value for B. Example:8:12 simplifies to 2:3. With new A=20, equivalent = 20:30.
Simplified ratio
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LCM / GCD Calculator
Enter multiple numbers separated by commas.
How it works:GCD: greatest common divisor using Euclidean algorithm. LCM: lowest common multiple, reduced pairwise across all numbers. Example: Numbers 12, 18, 30 → GCD 6, LCM 180.
GCD
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LCM
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Factorial Calculator
Calculate n! exactly, even for large numbers.
How it works: n! = 1×2×3×...×n. Uses JavaScript BigInt for exact precision. Limited to n=500 to keep the page responsive. Example:12! = 479,001,600. 50! = a 65-digit number.
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Values above 500 are blocked to keep the page responsive.
Prime Number Checker
Check whether a number is prime.
How it works: Tests divisibility up to √n using 6k±1 optimization (skipping even numbers and multiples of 3). If composite, shows the smallest factor. Example:97 is prime ✓. 100 is not prime — smallest factor 2.
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Mean / Median / Mode
Enter numbers separated by commas or spaces.
How it works:Mean: sum ÷ count. Median: middle value of sorted list. Mode: most frequent value(s). Computes all three plus total count. Example:4, 8, 6, 5, 3, 8, 9 → mean 6.14, median 6, mode 8.
Mean
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Median
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Mode
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Count
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Statistics Calculator
Standard deviation, variance, mean, median, mode.
How it works: Computes population std dev (σ) using √(Σ(x - μ)²/N) and sample std dev (s) using N-1. Also shows variance both ways. Example:12, 15, 12, 18, 20, 25 → mean 17, pop std dev 4.55.
Mean
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Median
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Mode
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Std Dev (pop.)
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Std Dev (sample)
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Variance (pop.)
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Random Number Generator
Generate one or more random numbers in a range.
How it works: Set a min-max range, choose how many numbers, and whether repeats are allowed. Uses a Fisher-Yates shuffle when unique numbers are requested. Example: Range 1-100, 5 unique numbers → 23, 67, 5, 89, 42.
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Sorting Visualizer
Watch classic sorting algorithms in action.
How it works: Generates a random array of 24 bars. Choose bubble, merge, or quick sort to watch each algorithm compare and swap elements with colored highlights. Adjust speed with the slider. Example: Watch bubble sort bubble the largest values to the right, one by one, with visual orange/yellow highlights.