Absolute and relative error
Absolute and relative error with an explained formula, a worked example and checks for invalid or unsupported inputs.
Choose a tool. The method, example and assumptions are included.
Absolute and relative error with an explained formula, a worked example and checks for invalid or unsupported inputs.
Arithmetic mean: Sum of values ÷ count
Find a term and the sum of the first n terms of a sequence with a constant difference.
Bayesian binary-classifier posterior: Apply Bayes’ theorem: posterior after a positive result = prior × true-positive rate / [prior × true-positive rate + (1−prior) × false-positive rate].
Binomial probability with an explained formula, a worked example and checks for invalid or unsupported inputs.
Combinations: n! ÷ [r!(n−r)!]; order does not matter
Complex number arithmetic: Use componentwise addition/subtraction, (a+bi)(c+di)=(ac−bd)+(ad+bc)i, and multiply by the divisor’s conjugate for division.
Covariance of paired data with an explained formula, a worked example and checks for invalid or unsupported inputs.
Event probability: Favorable outcomes ÷ total outcomes
Exact fraction arithmetic: Parse signed integer fractions with BigInt, apply the selected operation, normalize the denominator sign and reduce by the greatest common divisor.
Factorial: n! = 1 × 2 × … × n; 0! = 1
Frequency-table mean and variance: Treat each nonnegative integer frequency as a count of repeated observations.
Find the greatest common divisor and least common multiple of two or more integers, including exact large integers.
Find a term and finite sum of a geometric sequence, including ratio zero, one or negative ratios.
Histogram bin and frequency table: Split the observed range into equal-width bins, using left-inclusive/right-exclusive intervals except that the last bin includes the maximum.
Interpolate values from an XY table: Sort distinct x knots, find the two surrounding knots for each query, and linearly interpolate y between them.
Interquartile range and outlier fences with an explained formula, a worked example and checks for invalid or unsupported inputs.
Logarithm: log(value) ÷ log(base)
Matrix inverse and determinant: Use Gauss–Jordan elimination with partial pivoting on [A | I].
Matrix multiplication worksheet: Multiply compatible matrices with C[i,j] = Σ A[i,k] × B[k,j].
Calculate a two-sided normal confidence interval for a mean when population standard deviation is known.
Median: Sort numerically; use the central value or mean of the central two
Mode: Count exact numeric frequencies; return every value tied for most frequent
Moving average time-series worksheet: For each input row with enough observations, average that row and its previous window−1 values.
Normal distribution interval probability with an explained formula, a worked example and checks for invalid or unsupported inputs.
Percentile with linear interpolation with an explained formula, a worked example and checks for invalid or unsupported inputs.
Permutations: n! ÷ (n−r)!; order matters
Poisson event probability with an explained formula, a worked example and checks for invalid or unsupported inputs.
Polynomial definite integral by Simpson’s rule: Composite Simpson’s rule: h/3 × [f(a)+f(b)+4Σ odd interior samples+2Σ even interior samples], evaluating the entered polynomial with Horner’s method.
Polynomial value and derivative: Evaluate coefficients with Horner’s method.
Powers and roots: Raise the base to the supplied real exponent
Decompose a positive whole number into prime factors, exponents and the number of positive divisors.
Quadratic roots: Solve ax² + bx + c = 0 using the discriminant; real roots only
Range: Maximum minus minimum
Root mean square (RMS) with an explained formula, a worked example and checks for invalid or unsupported inputs.
Simple linear regression with an explained formula, a worked example and checks for invalid or unsupported inputs.
Solve a linear equation system: Apply Gaussian elimination with partial pivoting to an n×(n+1) augmented matrix.
Spearman rank correlation with ties: Rank each series with average ranks for ties, then calculate Pearson correlation between the two rank series.
Standard deviation: Sum squared deviations from mean ÷ N (population) or N−1 (sample); take square root
Plan a survey sample size for a proportion from a confidence level, absolute margin and optional population correction.
Variance: Sum squared deviations from mean ÷ N (population) or N−1 (sample)
Weighted average: Σ(value × weight) ÷ Σweights
Weighted median with an explained formula, a worked example and checks for invalid or unsupported inputs.
Welch two-sample t statistic and degrees of freedom: Set a = s₁²/n₁ and b = s₂²/n₂.
Express an observation as the number of population standard deviations above or below the mean.
Real nth root: Solve y^n = x over the real numbers.
Exponential decay and remaining amount: Remaining amount = initial amount × 2^(−elapsed time / half-life).
Exponential growth doubling time: Doubling time = ln(2) / ln(1 + growth/100), with a strictly positive growth rate.
Circular sector area: Sector area = π × radius² × central angle / 360 for angles from zero through 360 degrees.
Circular arc length: Arc length = radius × angle in radians = radius × angle in degrees × π/180.
Ellipse area: Ellipse area = π × semi-major axis × semi-minor axis.
Ellipsoid volume: Ellipsoid volume = (4/3) × π × a × b × c, where a, b and c are the three semi-axes.
Circular frustum volume: A circular cone frustum has volume πh(R² + Rr + r²)/3.
Torus volume: For a ring torus, volume = 2π² × major radius × tube radius².
Distance from a point to a line: For line ax + by + c = 0, perpendicular distance is |ax₀ + by₀ + c| / √(a² + b²).
Three-dimensional dot product: A·B = AxBx + AyBy + AzBz.
Three-dimensional cross product: A×B = (AyBz−AzBy, AzBx−AxBz, AxBy−AyBx).
Angle between two 2D vectors: Angle = arccos[(A·B)/(|A||B|)], returned in degrees from 0 to 180.
Polar and Cartesian coordinate converter: Polar to Cartesian: x=r cos θ, y=r sin θ.
Harmonic mean: Harmonic mean = count / Σ(1/value).
Geometric mean: Compute exp(mean(ln(value))) for positive observations.
Coefficient of variation: Sample coefficient of variation = sample standard deviation / arithmetic mean × 100.
Mean absolute deviation about the mean: Find the arithmetic mean, then average the absolute distances of observations from that mean.
Cohen’s d for independent samples: Cohen’s d = difference of means divided by pooled sample SD; pooled variance weights each sample variance by n−1.
Probability of at least one success: For independent equal-probability trials, P(at least one success) = 1−(1−p)^n.
Fractional odds implied probability: Implied probability = denominator / (numerator + denominator) × 100.
Finite population sample correction: Corrected size = ceiling(n₀ / [1+(n₀−1)/N]).
Polynomial synthetic division: Synthetic division divides a polynomial by x−r.
Modular exponentiation: Compute base^exponent mod modulus using exponentiation by squaring with exact BigInt integer arithmetic.
No sign-up. Tool inputs stay on your device.