Math calculators

Area of a rectangle, square, triangle, circle, trapezoid, parallelogram or ellipse in any unit, with the formula for each shape worked out step by step.

Find the mean, median, mode, sum and range of up to 10 numbers, with the work shown and a deviation table that explains what the mean really is.

Add, subtract, multiply, divide, take remainders and raise to powers with integers of hundreds of digits — exactly, well past what a normal calculator holds.

Convert between binary, octal, decimal and hexadecimal with the repeated-division working and the place-value table shown, exact to 2^53.

AND, OR, XOR, NOT and left/right shifts on two integers, shown in decimal, 32-bit two's-complement binary and hex, with every operation compared side by side.

Enter any one of radius, diameter, circumference or area and get the other three — with unit conversion and the π formulas worked step by step.

nCr and nPr, with or without repetition — exact answers for huge counts, the formula substituted, and a plain explanation of when order matters.

Margin of error and the confidence interval for a mean, using the exact t-distribution for small samples and z for large ones, with the critical value shown.

Pearson's r, r-squared, covariance and the line of best fit for up to 10 (x, y) pairs, with the deviation table and a plain reading of how strong the link is.

Exact odds of rolling a total with any number of dice and any number of sides — exactly, at least or at most — with the full distribution table and chart.

Straight-line distance between two points in 2D or 3D from their coordinates, with Manhattan distance, midpoint and the Pythagorean working shown.

Raise any base to any power — negative, fractional or huge — with the expanded multiplication, scientific notation and the rule that applies shown.

Every factor of a number, its prime factorisation, factor pairs, the divisor count and sum, and whether it is prime, perfect, abundant or deficient.

n! computed exactly with big integers up to 1000, in scientific notation beyond, plus the digit count, trailing zeros and the gamma function for non-integers.

Add, subtract, multiply and divide fractions and mixed numbers — exact simplified answers with the common denominator and every step shown.

Greatest common divisor and least common multiple of 2–4 whole numbers, with Euclid's algorithm written out line by line and the prime factorizations.

Least-squares slope, intercept, equation, r², standard error and a prediction for any x — from up to 10 data pairs, with the residual table shown.

Logarithm of any number to base 10, e, 2 or any base you choose — with the change-of-base step, an antilog check, and ln, log₁₀ and log₂ side by side.

Divide with the full long-division layout: every bring-down, each quotient digit, the remainder, and the decimal with its repeating block marked.

Exact jackpot odds for any pick-n-from-m lottery, with or without a bonus ball, plus the odds of every smaller prize tier — computed with exact combinatorics.

Determinant, trace, transpose and inverse of a 2×2 or 3×3 matrix, with the cofactor expansion written out and singular matrices called out explicitly.

a mod b with the quotient and remainder, showing where the mathematical modulo and the % operator in C, Java and JavaScript disagree on negative numbers.

Turn a z, t or chi-square statistic into a p-value, one- or two-tailed, with the critical value at your alpha and a plain-English verdict on what it means.

Percent error between a measured and an accepted value, plus absolute and relative error and whether you over- or under-estimated — sign conventions explained.

Find what percent one number is of another, take a percentage of a number, or calculate percentage increase and decrease — with the working shown.

Test any number up to a trillion for primality, get its full factorisation, the nearest primes either side, and how many primes lie below it.

Single-event, 'A and B', 'A or B', at-least-one and binomial (exactly k of n) probabilities as percentages, fractions and odds, with the rule applied shown.

Find the hypotenuse or a missing leg of a right triangle with a² + b² = c², plus its area, perimeter and angles — every step shown, any unit.

Solve ax² + bx + c = 0 with the quadratic formula — real or complex roots, discriminant, vertex, axis of symmetry, factored form and a graph of the parabola.

Draw whole numbers from any range, with or without repeats, from an explicit seed — so the same seed always reproduces the same draw and anyone can check it.

Simplify a ratio, solve a proportion (A:B = C:?) or split a total in a given ratio — with the GCD, cross-multiplication and each part shown.

Solve a right triangle from two sides, or a side and an angle: all three sides, both acute angles, area, perimeter, altitude, inradius and circumradius.

Round to any decimal place, to tens or thousands, or to N significant figures — half-up, banker's, floor, ceiling or truncate — with the rule explained.

How many people to survey for a given margin of error and confidence level, using Cochran's formula with the finite population correction.

Type a whole expression and get an exact answer: brackets, powers, roots, logs, trigonometry in degrees or radians, and the order of operations applied properly.

Convert any number to scientific, engineering and E notation with chosen significant figures, or expand a × 10ⁿ back to a plain decimal — exactly, no float noise.

Arithmetic and geometric sequences: the nth term, the sum of the first n terms, the first ten terms listed, and the infinite sum when the series converges.

Slope, y-intercept and the equation of the line through two points, plus distance, midpoint, angle and the perpendicular slope — with rise-over-run shown.

Square roots, cube roots and nth roots with the radical simplified (√72 = 6√2) via prime factorization, plus the number squared and cubed.

Population or sample standard deviation, variance, mean and standard error for up to 10 values — with the full deviation table so you can see every step.

Surface area and volume of a cube, box, sphere, cylinder, cone, square pyramid, capsule or torus, in any unit, with the formula and the arithmetic shown.

From three side lengths get the area (Heron's formula), all three angles, perimeter, heights, inradius and circumradius, and whether it's right, acute or obtuse.

Dot product, cross product, magnitudes, the angle between two 3D vectors and the projection of one onto the other, with every step written out.

Volume and surface area of a box, cube, cylinder, sphere, cone or pyramid in any unit — cubic meters, liters, gallons, cubic feet — with the formula shown.

Weighted mean of up to 8 values with any weights — percentages, credit hours or dollars — showing what each item contributes to the answer.

Turn a raw value into a z-score, percentile and p-value using the exact normal distribution, with the standard z-table and the arithmetic shown.