Math
1,470 math calculators: percentages, fractions, equations, geometry, trigonometry, statistics and number theory. Each one shows the method in plain words, so you get the answer and understand how it was reached, free in your browser.
Fraction calculator
Enter 2/4 and get 1/2, already in lowest terms, plus its mixed form and an exact decimal. Add, subtract, multiply or divide two fractions with no rounding…
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Percentage calculator
Six percentage questions in one place: how much 20% of 150 is (30), what share one number is of another, how much something rose or fell, and what it cost…
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GCD LCM calculator
Enter 12 and 18 and get a GCD of 6 and an LCM of 36, or pass up to 20 numbers in one go. Handy for reducing fractions, finding common denominators and lining up…
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Circle calculator
Give one measure of a circle and get all four: a radius of 1 returns a diameter of 2, a circumference of 6.283185 and an area of 3.141593.
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Quadratic equation solver
Type a, b and c and get both roots with the discriminant: x² − 3x + 2 = 0 has a discriminant of 1 and the roots 2 and 1.
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Pythagorean theorem calculator
Enter any two sides of a right triangle and get the third plus the area: legs of 3 and 4 give a hypotenuse of 5 and an area of 6.
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Permutation & combination calculator
Find how many ways you can pick r items out of n: choosing 2 of 5 gives 10 combinations when order does not matter, while permutations count every order…
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Bell number calculator
B(5) is 52: there are 52 ways to split five distinct items into non-empty groups when the order of the groups does not matter.
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Equilateral triangle calculator
An equilateral triangle with a side of 2 has a height and an area of about 1.732051 and a perimeter of 6.
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Euler triangle OI distance calculator
With a circumradius of 10 and an inradius of 3, the circumcenter and the incenter are about 6.324555 apart, since the squared distance is 40.
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Intersecting chords calculator
With AP of 3, PB of 4 and CP of 2, the missing PD is 6, because both chords share the product 12. Enter any three of the four segments of two crossing chords…
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Jacobsthal number calculator
Enter a whole number n from 0 to 40 and get the nth Jacobsthal number exactly: the sequence runs 0, 1, 1, 3, 5, 11, 21, 43, and J(40) is 366503875925.
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Oblique cylinder calculator
A cylinder with radius 3 and perpendicular height 10 holds about 282.7433 cubic units, however far it leans.
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Spherical excess calculator
Enter the three angles of a spherical triangle and get its excess, area and share of the sphere: angles of 1.2, 1.1 and 1 radians on a sphere of radius 1 give…
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Subfactorial calculator
Count the derangements of n items, the arrangements where nothing stays in its original place: the subfactorial of 4 is 9, and you also get the chance that a…
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Torus sector calculator
A torus with major radius 5 and tube radius 1, swept through half a turn, has a volume of 49.348022 and an outer area of 98.696044.
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Tribonacci number calculator
Position 6 of the Tribonacci sequence holds 7: each term is the sum of the three before it, starting from 0, 0 and 1.
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Trirectangular tetrahedron calculator
A corner tetrahedron with perpendicular legs of 3, 4 and 5 has a volume of 10 and a total surface of 37.3654.
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Sphere calculator
Enter a sphere's radius and get its diameter, equatorial circumference, surface area and volume at once: a radius of 1 gives a surface of 12.5663706144 and a…
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Polygon apothem calculator
Give the number of sides and one length you know, and the whole regular polygon comes back: a hexagon with sides of 2 has an apothem of 1.732051, an area of…
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Abjad numeral converter free online
Alif counts as 1, ba as 2 and ghayn as 1000 in the classical Eastern abjad table. Turn a number from 1 to 1999 into letters, read letters back as a total, or…
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Age ratio calculator
If two ages are in the ratio 2:1 today and 3:2 in 5 years, they are 10 and 5 now. Enter both ratios and the gap in years to get the present and future ages for…
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Boat and stream speed calculator free online
A boat doing 10 in still water against a current of 2 moves upstream at 8 and downstream at 12. Work the classic boat-and-stream problem either way: from boat…
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CP SP MP calculator
Work through classic profit-and-loss questions: with a cost of 100, a marked price of 150 and a 10% discount, the selling price is 135 and the profit is 35, or…
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Hebrew numeral converter and gematria free
Write a whole number in Hebrew letters or read Hebrew letters back as a number: 5 becomes ה׳ with its geresh, and forty-two is mem plus bet.
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Largest remainder seat allocation free
Turn vote totals into whole seats with the largest remainder method: 416000, 338000 and 246000 votes for 10 seats under the Hare quota give 4, 3 and 3 seats.
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Maya vigesimal numeral converter free
Convert whole numbers into Maya base-twenty numerals and back, written as the plain words shell, bar and dot: 0 is a single shell, and every place from 1 to 19…
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Pie chart angles from values free online
Values 1, 1 and 2 add up to 4, so they become a quarter, a quarter and half of the circle. Enter any list of values or weights to get each slice's angle in…
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Pipes and cisterns calculator free online
Two pipes that fill a tank in 4 and 6 hours fill it together in 2.4 hours. Enter how long each inlet takes to fill the tank and each drain to empty it, and get…
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Sainte-Laguë seat allocation calculator free
With 5000, 3000 and 2000 votes and 5 seats to fill, the Sainte-Laguë method gives the three parties 3, 1 and 1 seats.
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Arithmetico-geometric series sum
With a first term of 1, a difference of 1, a ratio of 0.5 and 5 terms, the sum is 3.5625. Enter the arithmetic start and step, the geometric ratio and how many…
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Chain discount / net price factor
Turn a chain of trade discounts into one net price: a list price of 100 with twenty percent and then ten percent off comes to 72, a net price factor of 0.72…
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Hexagonal prism calculator
A hexagonal prism with a side of 2 and a height of 5 holds about 51.961524 cubic units. Enter both lengths and get the volume, the base area, the lateral area…
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Markdown percentage calculator
Turn two price tags into a markdown percentage: an item cut from 80 to 60 is 25% off, with 20 taken off.
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Motzkin number calculator
Get the Motzkin number at any position n, built by the standard recurrence from two starting terms equal to 1: position 0 gives 1, and each later term adds the…
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Power of a point calculator
Enter the distance from a point to the center of a circle and the radius, and get the power of the point, d² − R²: at a distance of 5 from a circle of radius 3…
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Regular tetrahedron calculator
A regular tetrahedron with an edge of 2 has a volume of about 0.942809 and a surface area of 6.928203.
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Roman chronogram calculator
In the phrase “aMore paVLVs” the Roman letters M, V, L and V add up to 1060. Type any phrase and the calculator finds every M, D, C, L, X, V and I, lists them…
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Square pyramid calculator
Enter the base side and height of a square pyramid and get its volume, slant height, lateral area and total surface at once: a side of 4 and a height of 3 give…
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Stair rise and run calculator
Turn a floor-to-floor height into equal steps: a total rise of 280 with a target riser of 18 gives 16 risers of exactly 17.5, 15 treads and, with treads 25…
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Tangent-secant theorem calculator
With a tangent of 6 and an outer secant part of 4, the whole secant is 9, because PT² = PA·PB and both sides give 36.
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Wastage allowance calculator
Find the quantity to order so that, after a known share is wasted, you still keep what you need: 100 units at 10% wastage means ordering 111.1111.
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Hedges g effect size
Compare two groups on a common scale: with means of 10 and 8, standard deviations of 2 and 30 people in each group, Cohen's d is 1 and Hedges' g is 0.987013…
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Matthews correlation (MCC)
With 50 true positives, 40 true negatives, 5 false positives and 5 false negatives, the Matthews correlation coefficient is 0.79798.
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Absolute value equation solver
For |2x − 3| = 5 the two roots are −1 and 4, found by setting the inside equal to 5 and to −5. Enter the three numbers of your equation to get its ordered…
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Finite series partial sum
Check a partial sum without adding by hand: the arithmetic sequence starting at 2 with difference 3 gives 2, 5, 8, 11 and 14 for indexes 1 to 5, a total of 40.
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2×2 system by substitution
For 2x + y equal to 5 and x − y equal to 1, isolating x gives 2.5 minus 0.5y, and substituting leads to the point (2, 1).
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Binomial coefficients row
Enter a row number and receive every binomial coefficient on that line of Pascal's triangle: row 5 gives 1, 5, 10, 10, 5, 1, six exact values that never lose…
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Capsule volume & surface area
Get the volume, surface area and total height of a capsule, a cylinder capped by two hemispheres: a radius of 2 and a straight section of 5 give a total height…
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Hyperbola eccentricity
Measure how widely a hyperbola opens from its two semi-axes: 3 and 4 give a focal distance of 5 and an eccentricity of 5/3.
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Polygon interior angle calculator
Enter how many sides a regular polygon has and get its angles: in a pentagon the interior angles add up to 540°, each one measures 108° and each exterior angle…
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Star polygon area calculator
Get the filled area of a regular star from its number of tips, its density and the radius to the tips: the classic five-pointed star {5/2} on a circle of radius…
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Triangle incenter calculator
Find the center of the largest circle that fits inside a triangle: for the vertices (0, 0), (4, 0) and (0, 3), the incenter is (1, 1) and the inscribed circle…
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Harmonic series calculator
Pick a whole number n and get the harmonic series added up to 1/n: the first 10 terms come to 2.928968253968.
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Prime factorization
Break any whole number from 2 upward into its primes: 360 is 2³ · 3² · 5, or 2, 2, 2, 3, 3 and 5 listed one by one.
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List all ordered compositions of an integer
The number 4 has 8 compositions, from 1+1+1+1 to 4 itself, and this tool lists every one of them in a fixed order with the count beside it.
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Discrete logarithm solver
Ask which power of 2 leaves 5 modulo 13 and you get 9, because 2^9 ≡ 5 (mod 13). Enter a base, a target and a prime modulus to find the smallest exponent, with…
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Divisors of a number
12 has 6 divisors, 1, 2, 3, 4, 6 and 12, and they add up to 28. Enter any positive whole number up to one trillion and get the full ordered list, the count and…
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Is prime checker
Checks whether a whole number is prime and, if not, shows the smallest divisor that proves it: 97 comes back prime, with no divisor at all.
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Durbin-Watson statistic calculator
Six residuals that keep switching sign give squared differences of 3.19 against squared residuals of 1.19, a Durbin-Watson d above 2.5 that hints at negative…
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