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  • Hex Calculator
    Enter two hexadecimal numbers, choose add, subtract, multiply, or divide, and see the result instantly in hex for quick, accurate calculations.
  • Hex to Decimal Converter
    Enter a hexadecimal number to get its decimal value and see the binary equivalent. Fast hex-to-decimal conversion for math, coding, and data tasks.
  • Fisher's Exact Test Calculator (2x2)
    Compute the exact p-value for a 2x2 contingency table using Fisher exact test. Get the hypergeometric probability and two-sided p-value instantly.
  • Variance Calculator
    Calculate variance easily with this online tool. Enter comma-separated numbers to determine the spread of data points from the mean. Ideal for statistical analysis and data interpretation.
  • Time Zone Converter
    Calculate time differences across the globe with this Time Zone Converter. Easily compare multiple time zones, plan international calls, and avoid scheduling conflicts for seamless global communication.
  • Poisson Distribution Calculator
    Compute the Poisson distribution: probability mass f(x;lambda), lower cumulative P(X<=x), and upper cumulative Q(X>=x) tabulated over a sequence of x values.
  • Numerical Integration over (a, b) — Double-Exponential (Tanh-Sinh) Method
    Compute the definite integral of f(x) on a finite interval [a, b] with Double-Exponential (Tanh-Sinh) quadrature — robust even for endpoint singularities like 1/sqrt(x).
  • Standard Deviation Calculator
    Calculate sample standard deviation from comma-separated numbers, and get mean, variance, median, min, max, count, and sum in seconds.
  • Factor Calculator
    Calculate factors of any number with this Factor Calculator. Find all divisors quickly and easily for mathematical analysis, problem-solving, and understanding number properties.
  • Vote Percentage Calculator
    Calculate and visualize vote percentages for multiple candidates with our easy-to-use Vote Percentage Calculator. Input votes, see instant results, and view a colorful bar chart representation of the election outcomes.
  • Semi-Infinite Interval Integration by Double-Exponential (DE) Formula
    Compute the integral of f(x) over [a, infinity) using Double-Exponential (DE) quadrature for algebraically-decaying integrands. Universal numerical method.
  • Double-Exponential (DE) Quadrature: Integral over (-∞, ∞)
    Numerically integrate any f(x) over the whole real line (-∞, ∞) using Double-Exponential (tanh-sinh / Takahasi-Mori) quadrature. Set precision in significant digits.
  • Stem and Leaf Plot Generator
    Free stem-and-leaf plot generator. Paste your numbers to build a stem-and-leaf diagram with single or split stems, plus mean, median, mode and standard deviation.
  • Time Duration Calculator
    Calculate time duration quickly and accurately with this Time Duration Calculator. Input start and end times to find the exact interval between two points in time.
  • Hijri Date Converter
    Enter a Gregorian date to convert to the Islamic (Hijri) calendar and instantly see the Hijri date, year, month, and day.
  • Prime Number Primality Checker
    Check if a number is prime or composite. Lists all factors, the previous prime and next prime using a fast trial-division primality test.
  • Studentized Range Distribution Probability Calculator
    Compute the lower and upper cumulative probability of the studentized range distribution (Tukey q statistic) for a quantile q, sample size r, df nu and c groups.
  • Book Page Calculator
    Free book page calculator: enter total pages and your current page to instantly see pages read, pages left, and percent complete with a progress bar. Try it now.
  • Height Converter: cm to Inches and Feet
    Convert a height in centimeters to inches, decimal feet, and feet-and-inches with a fraction you choose (1/8, 1/16, etc.). Exact 1 in = 2.54 cm.
  • Fran CrossFit Pace Calculator
    Estimate calories burned in a CrossFit WOD or HIIT session using the MET formula. Enter body weight, duration and intensity (MET 8–12).
  • Age Multiples Word Problem Calculator
    Solve the classic age word problem: a parent is n times the child's age now and m times after some years. Instantly find both current ages.
  • Z Critical Value Calculator
    Find the z critical value for any significance level α. Supports one-tailed (zα) and two-tailed (±zα/2) tests using the inverse normal distribution.
  • Vietnam Household Business Tax Calculator
    Estimate VAT and personal income tax for a Vietnamese household business under Decree 141/2026 and 253/2026 across four revenue bands.
  • Percentage Growth Calculator
    Enter initial and final values to calculate percent change using (final - initial)/initial * 100 and see how much it increased or decreased.
  • Classes You Can Skip Calculator
    Free bunk calculator: find how many classes you can skip while staying above your required attendance percentage. Enter attended, total and required %.

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